Logically, I would think if you wore your baby constantly for five months and they were 'meant' (I use that term loosely) to roll at four then the fact that they don't have the opportunity to roll means they aren't going to do it until they stop being worn IYKWIM. Clare, I know this example is different to your timelines but hope that makes sense.

Will this matter? I wouldn't think so. I think they catch up and do things when they're ready. A baby that is worn because he or she doesn't like being on the floor is not going to roll anyway are they, worn or not?

My baby always HATED tummy time so I ignored the by-the-book MCHN who told us that we should give our babies 3 x 20 minutes of tummy time each day. Absolutely pointless trying to do that if she didn't like it and cried. What's that teaching her? So I just let her be and hey presto she went from hating tummy time to literally overnight being the rolliest polliest baby around. With, I should add, the proudest look on her face. I just tell people she doesn't bother doing something until she's mastered it!

So don't worry - I think by all means keep trying to give your son time on the floor but if he's not liking it, just wait until he does. He'll get the idea.