K.W.
We were given some great advice when we were tackling this same problem in late July. We only concentrated on the day potties first and the night honestly just fell into place. We didn't know how to tell him he could get out of bed and know that he would return to "his" bed and not climb into ours downstairs (his morning ritual). We were on vacation when he got up and went potty by himself one night.
Our doctor was actually VERY surprised when he was already potting at night (so I don't think that it usually happens this way)
Our little one seemed to just follow along. He would ALWAYS SOAK his diapers aswell and honestly it seemed to slow down as he reached potty training readiness :)
Hope this helps :)