Baby still not rolling?

Chelsea

So my baby is 15 weeks old today. We do lots of tummy time and he’s able to get his head high and does it without fussing about 5-10 minutes. Sometimes he just lies on his stomach with his head down but he’s not fussing as much so I call that a win but he’s not rolling and I’m trying not to worry about it. I encourage him with toys and showing him how by assisting him to roll but nothing 🤷‍♀️ trying not too stress here....