Both times I did nothing. Dd1 was 3.5 and told me she wanted to wear undies to bed. I said she had to be dry 5 nights in a row and we did a chart. She was dry pretty much 5 nights from the word go so she went to undies. Dd2 was the same but was night trained 2 weeks after being day trained. She just decided.

I also made sure they had their last evening drink with dinner and went to the toilet before bed. Once they were dry overnight for a few months the drinks thing relaxed. The only accidents we have had have been when they have been sick with fevers which isn't unusual.