The way things are around here at present (I still have a teenage kid living here) I can't openly wear mine unless he's out of the house. Also, I still only wear for fun / excitement / relaxation and because that's mainly how I get myself off these days (for the same reason that I can't go around wearing my diapers, I also can't ever find time to have fun with my wife, either).
So when I wear to bed it's usually a last minute, spur of the moment idea. I usually put them on as I'm going to bed. If I think I may be wearing that night, then no, I won't pee before I put them on, and I will drink a big 24-oz cup of water to ensure that I have to pee a lot overnight.
Over the 40+ years I've been into this I've pretty much conditioned my brain such that as soon as I have diapers on, I just seem to magically become incontinent and start wetting them. So usually once they're on I'll lay down in bed, stretch out, and enjoy feeling that first warm wet pee going into my thick, soft, flannel cloth diapers.
In fact, I actually like doing this as, getting them wet causes the stiffness of the material to relax a bit, which means they fit more comfortably. Since I sleep on my side, this means that I don't have so much bulk between my legs because the damp diapers better adjust to fit the position I'm in.
Sometimes having them on makes me so diaper-horny that I get myself off before I can go to sleep. Like many people here, after getting myself off in my diapers I have to fight the urge to take them off for about half an hour (diaper wearing has always been a "binge and purge" sort of thing for me, even on a small case by case basis). But by then I'm usually almost asleep.
I'll then wake up several times throughout the night, roll over onto my back, wet them, and go back to sleep. And waking up the next morning in thick, warm, soaking wet, pee-reeking diapers and plastic panties is the most wonderful feeling in the world!