Rolling 20 weeks

My baby will be 20 weeks old on Thursday and just started to show signs of rolling... he reaches towards toys with both hands if he is on his back and the toys are next to him but either only his upper body or his legs turning to the side..it looks like he hasn't got the two moves together to actually roll from back to side...🤷‍♀️

I don't feel he is behind his age but i keep seeing posts about September babies already rolling for 3-4 weeks now...

Should I worry that he isn't rolling yet?