I was definitely 'trained' to wee before bedtime and now can't go to sleep unless I've had a wee beforehand to the point that if I wake up I often have to get up and go to the loo before I can go back to sleep!
My DC2 potty trained herself at 22 months! She went dry at night before her big brother too. It was when she woke me at 5am needing me to take her nappy off as she needed a wee I realised that she was ready (just over 2) and I couldn't be doing with getting up at 5am so put a potty in her room.
It coincided with her refusing to go to bed! She's quite a forceful character and I avoided direct confrontation except where I felt it was a matter of safety. So I let her play and put herself to bed (checking on her from time to time), thus giving her a sense that she had some control but actually she went to bed earlier this way!
What I noticed was that some nights she had a wee, some nights not and it had no affect on whether she was dry or not!
With DC1, I did try to get him to wee before bedtime. He took a long time to go dry in the day (getting on for 4) and even longer at night (6ish, I think, can't remember). Once he got it though he really got it. Didn't always want to go before bedtime and, I think, rather resented me telling him that he needed to which was different to what his body told him!
Incidently, DC3 was different again!
However, all 3 still don't always go before bed and, even more interestingly, don't always go when they get up either. And they are drinking plenty before you ask! So I think a lot of this needing to go before bedtime/on rising is training and habit.
Oh yes, I also used to try to limit drinks before bedtime but they couldn't understand why they couldn't have a drink if they were thirsty. DC1 still regularly drinks 1/2 pint milk just before bed and at 13 I'd be pretty surprised if he wet the bed!