My little girl is now 5 mths old and is starting to move around a little but isn't rolling. Don't let your health nurse fill you with fear saying he needs to roll now. I have two others and with my second she didn't have as much tummy time etc as the first and she ended up crawling at the same time anyway so don't worry to much when they do do it you'll be hoping they were little again.
Ngari 25, mother of 3