Anytime I complete a “full thought” of code that compiles and runs I check-in. This usually ends up being anywhere between 15-60 minutes. Sometimes it could be longer, but I always try to checkin if I have a lot of code changes that I wouldn’t want to rewrite in case of failure. I also usually make sure my code compiles and I check-in at the end of the work day before I go home.
I wouldn’t worry about making “too many” commits/check-ins. It really sucks when you have to rewrite something, and it’s nice to be able to rollback in small increments just in case.