When do babies start to flip/roll over?

My boy flipped over at abt 2.5 months and tt's considered v early. He's naturally v active and started standing independently at 6 mths, walked at 8 mths. Contrary to what doctors said, I did not swaddle my boy much as he likes to wiggle ard and I let him discover his hands and feet. But of cz it depends on the baby. Most babies need to swaddle to slp but a few hates it like my boy. My mom was an infantcare teacher and she said typically babies start rolling ard 3-6 mths. Doing lots of tummy time helps as it strengthens baby's neck and back. Once baby starts rolling, do hold him up to stand on his feet so that he gets used to using his leg muscles.