How can I give my coworker the training in the time I have left?

You don't, this is your boss's job to assign not yours. When you resign from the company, your boss will decide who ( if anyone ) will be trained to fill your role. They will also decide if you will be the one doing the training or not.

Present the training activity to both the trainee and your managers as improving the bus factor. It is prudent to have at least two people capable of doing any job.

Talk to your manager first, so that you are certain who they want you to train.

Training the wrong person could create an extremely difficult situation when you resign. Training person X would make them expect to be your successor, and leave them feeling resentful if your manager prefers person Y. Your X training effort would have been wasted, and you would have to do hurry-up training of Y during your notice period.

Don't make plans for other people or assume you know what's best for them.

This includes the colleague you want to train to be your replacement, and your employer.

You've got good intentions here and that's commendable. But the fact is, your version of what people will want to do once they learn you're leaving is likely wrong.

For instance, it's very possible that your colleague simply isn't interested at all in doing your job. Or perhaps they're planning to leave themselves. Or even if they'd be interested, the employer would have no intention of promoting them into the position anyway. Or, maybe with you leaving they'd restructure the team(s) and your position would cease to exist. The list goes on.. you just don't know what will happen. What you see as an obvious opportunity, worth twisting yourself in knots to give to your colleague, may just turn out to be nothing.

If you want to leave, and want to give your colleague the option of the opportunity to replace you, then secure another position first and then do the following:

• Give your contractually agreed notice to your employer. Mention nothing about your colleague at first, but ask them if they're OK with you telling people straight away.


• 
  If yes, then go to your colleague and ask them privately if they'd be interested in your job.


• 
  If yes, suggest a handover training plan to best prepare them for this. Make sure they know this is you suggesting this, not the employer, and you'll suggest it to the employer if they agree.


• 
  Only if they are OK with it, then go back to your employer, sell your colleague as a good potential replacement, and suggest the handover plan.


• 
  If your employer agrees it's a good idea, implement it.

Assume nothing. Do everything in the open. Make suggestions, sure, but let everyone involved take their own decisions about what will happen at every stage before you proceed.

"Getting hit by a bus"

You're training someone to do what you do so that if you're out sick one day, get hit by a bus, or have some other emergency your company has someone ready and trained to fill in your role until you come back (or don't).

Its just a level of insurance that your company's management should see as a "good thing" not something to fear that you're intending to leave. It just so happens to let you extricate yourself without leaving the company in the lurch when you do hand in your resignation.

Before all of that surreptitious training the easiest and best way to do this is to write a whole bunch of great documentation and comment your code. That way no matter who gets picked after you're gone will have a good starting position. Even the person that comes after them will benefit (especially if it is kept up to date.) You also won't need to worry so much about training them up yourself, they can learn after you leave.

But if you really want to try to secretly train this specific person you'll need to get them to start working on the system. You could try claiming illness or just being overworked and ask if they could cover just this one "little task" for you. Start getting them to work on little bits of the system. Let them ask you a bunch of questions about it.

This isn't really a morally okay thing to do. Your co-worker isn't going to appreciate it while you're doing it. You may get in trouble for not doing your own work. The only way (except for good doco) that they will learn about the system is to work on it. So you'll need to find some way to get them to do that. (Alternatively just tell your co-worker what is going on and let them study the system and ask you questions. As long as they won't tell your boss.)

My bosses cannot know that I am considering leaving, because they will
make my worklife miserable.

I want my coworker to be well established to fill my role and be in
line for promotion and a good opportunity after my departure. We are
not close, but I know that they are in such a situation as to benefit
greatly personally and professionally. So I also do not want to let
them in on my plan. Especially as it may cause bad repercussions for
them if they are found to knowingly go along with my plan.

So your plan is to sneak around and be deceptive, both to your bosses and your colleague?

That doesn't sound like a good plan.

I can understand your not wanting to tip your hand to your bosses, but involving your colleague in your plan without their knowledge is deceptive, dishonest, and could potentially put their job in jeopardy.

I'd caution you to rethink your approach to this issue.

Document, Document, Document.

This is something you should be doing anyway, but if you don't, write down the things that you do as part of your job. Write down all the details, all the things that you hit your head against, how to overcome them, basically anything that you'd give to anyone you would consider training. It is not a replacement for training but it will make the training process that much easier when you do leave. It's also easy enough to use as a cover as 99% of the time, documentation needs no explanation as to why it might be a good idea.

You have no control on who replaces you

When you leave, the documentation will likely be picked up by the person the company chooses to replace you. This may align with your pick, it may not. You don't have any hope of changing this, especially post-departure.

Think a bit further. You are trying to train person X. Person X will interpret that as you wasting their time. X will go to their manager and say “this guy is wasting my time, please stop them”. Now your boss finds out, and you are in the worst possible position. Worst case X or someone else gets your job immediately. Because your boss will figure out you were leaving, and going behind his back by training someone he wouldn’t consider as your replacement.

PS. Reading your other posts where you say that you have so many projects that you cannot finish, I can't help wondering that this project trying to teach someone your job without being asked isn't just procrastination?

You don't because the only ethical way to do what you suggest is if you could train this person on your own time, on your own equipment, outside of business offices. Or if your employer has a loop-hole allowing you to spend hours training people however you like which it doesn't sound like.

But perhaps I'm becoming the thing I hate, but being partial myself?

Absolutely. The fact you have your job proves that your employer is not as bad as you paint them. Unless you're saying that you don't really deserve the title/role you have. So we know that they aren't always bad & that they (according to you) aren't always good. That describes like 99% of the employers people actually want to work for, you know.

At any rate it's your employer's prerogative to manage employee positions. Not yours. Sometimes employers ask employees for advice/opinions on promotions but that's not the case here. Maybe if you told your employer that you're leaving they would give you the opportunity to help them train/select someone. Obviously you'd also face the risk of being shown the door before you want.

• Would having someone review your documentation help you in you make them clearer?


• Would having your code reviewed help reduce bugs?


• Would having someone who could fix problem while your are on holiday help your employer?


• Would having another developer try building the software their machine help check the company can recover from a problem with your machine?

Is there any think else that needs to be done to train a replacement?