Rolling over

How can I encourage my 3.5 month old to roll over from his tummy to back. Or when do babies start to do that?

He hates tummy time and I always try and put him on his tummy but he ends up crying after like 30 seconds of being on his tummy I’ve tried so many different toys I’ve tried laying next to him I’ve tired talking to him running his back like everything to get him happy while on his tummy he can do a push up he is just being a cry baby about it basically 😂