My DD started naturally staying dry at night on her own. After I realized that it had been awhile since we had had a wet pull up, we started tracking it. Not for her benefit, but for mine. I told her when she filled a chart, she could wear her panties to bed. She had already been staying dry so it wasn't anything new that I was charting, but she does LOVE her charts! The chart was 30 days long. I wasn't comfortable keeping her in panties until that length of time. She has only had one accident in the 5 months that she has been wearing panties to sleep and it was super minor (in the morning and she felt and stopped it, still having some left for the potty. It didn't even get her bed wet.) She was ready on her own so we had success.
A tip for preparing: I double make her bed. She has a waterproof mattress pad, then a fitted sheet, then an old waterproof crib sheet (I cut the fitted part off so it would lay flat. It is bigger than the flat pads I found in the stores) then another fitted sheet on top of that. If there is an accident in the middle of the night it is much easier to just pull off the top stuff and still have a mostly made bed when you are still half asleep. We have used this method when she threw up in her bed and clean up was much quicker also.
Good luck and just make it a positive experience for your child. Use the double made bed method to save your sanity as well. Oh yeah, my daughter stayed dry when she was 35 months old. Almost 3. She had been dry during the day for about 6 months prior to that.