Honestly there's no need to bathe your snake unless there's stuck shed etc.. All you'll do is add stress to a time when they're already a little stressed due to going into shed. Try not to handle too much during this period.
When you say warm bath, how warm? If it felt warm to your hand it was probably too warm for your CRB as they like quite mild temp ranges really.
Other than that, welcome to the wonderful world of snake keeping.
A rainbow boa is a good choice, they're stunning animals and especially when they're in sunlight. Got any pics of the little guy to show us?