If you think about it, the "physics" of how his powers work keeps changing and has never been fully understood. In some versions, he's flying out of the rocket. In others, it takes so long to absorb yellow solar radiation, he doesn't develop any until puberty. I'd like to think the "realistic" solution lies somewhere in the middle. He'd start to develop powers at least within his first couple years on Earth but certainly not right out of the rocket. His heat vision seems to be stored up radiation. Which suggests he has to absorb a certain amount first before he can use it. I think Byrne kind of had the right idea with a telekinetic field around his body (remember Superman #1 after the reboot where he lifts an entire building into orbit? He explains a lot of it there). Maybe the Snyder version does that and they just don't come right out and say it. I think realism is important but I also think you can get too bogged down in that sort of thing. One of the things they did that I liked was having the Kryptonians having trouble breathing when they first come to Earth. That makes sense to me. In terms of the physics of how his powers work, I think the most realistic was probably Kingdom Come. After so many years on Earth he had absorbed enough solar radiation that he was immune to both Kryptonite and nuclear blasts. And he could hear all the way from Metropolis to Gotham and the entire JSA couldn't hold him down.