I've almost wet the bed. I tried going 24/7 for two weeks and I definitely almost wet my diaper while asleep, I just didn't since I was dreaming and was aware of it too. I had to double check if I really was wearing one so I woke myself up at that thought.
If you really wanna wet the bed, it definitely takes less than 3 months to achieve it, just be prepared on what you're going in for.
So in my experience, you really have to train yourself than simply wearing diapers 24/7 or else it will take you that long to magically wet your diaper in your sleep one day.
To start off, when you get the urge, small or big, breathe, have patience and just release, absolutely no pushing of your bladder at all. This will take lots of time to just pee, you can close your eyes to focus if you want. This will ache a bit but finally, you're peeing, but in a very slow way, which is reasonable, a weak stream without having to push yourself is a great step to incontinence you desire. Now for albeit three days more or less repeating the same process you'll be able to relieve yourself with a single sigh.
Next step, mind your positions when wetting yourself, you'll see that maybe sitting or standing up were your position most times you went, if you feel confident with those positions, try peeing your diaper in the most unconventional ways you can possibly execute, without leaking if possible. First thing you can try is peeing while laying down, this will be very helpful since you'll be sleeping in this position. Get comfortable, diaper snug, and repeat the process I told you, breathe, relieve, and you'll get a warm stream after. It would be best to not touch or check your expanding diaper as you do, being mindful of your doing could lengthen the process to achieve night incontinence. Now repeat this process, alot. Next positions are laying on your stomach, laying down on side, with your legs close to your chest, and legs spread. Heck you could even hug a pillow close to your crotch as you pee.
The key to this training is to not be mindful of when you go. You feel the urge? Sigh, relief, don't think about it and get on with what you were doing currently. Touching your diaper before, during, or after wetting will make you mindful of it. You can touch it after a considerable time passed.
There is no need to intake more fluids more than what you usually drink.
Don't be too mindful of your urges, that's also a no-go.
And that's it, that's how in two weeks of 24/7 diaper wearing my 14-year old self almost wet his diaper in his sleep.