Is this normal??...

Alivia • I’m 23 and married to my love, I have a 3 yr old girl and a angel baby boy was born December 3rd @ 37 weeks n was stillborn.. our rainbow 🌈 baby Boy #3 Tobias is finally here

So my son was born on April 4th and I’ve seen a few of my friends that had babies around the same time n there little ones are already starting to roll over, n we try to do tummy time at least 2/3 times a day or just whenever nothing else works n he just refuses to roll over he just lifts his head up n stares at the tv or if one of us is playing with him any advice on how to get him to would be helpful, my daughter started to around this time or a little later so idk