DD1 was day trained at 2.5 and then she told us she wanted to wear undies to bed at 3. As Olive said I would make the bed up double layered so that it was easy to change for accidents.

Initially she started on naps with undies and she was fine. When she said she wanted to go all night I told her she needed to be dry 5 nights in a row and she could wear undies (she was still flooding her night nappy at this stage so we didn't think she was ready). Well, when we said that, the next night was the start of 5 dry nights in a row! So she wore undies to bed and has ever since.

The main thing for us is to remember to make sure she goes to the toilet before bed as the times that she has wet the bed tend to be when we have forgotten to do that.