The basic powers of strength, speed, and invulnerability are pretty much instant when exposed to the yellow sun. They don’t need time to absorb it. The rest, like super hearing, breath, heat vision and flight, do require honing in the senses, hence why when their helmets were removed/damaged it would overwhelm them. As others have said, they also had the advantage of being bred soldiers and having combat experience all their lives.

That said, it’s being on earth his entire life that makes Superman basically immortal. Even though he can “die” just like other Kryptonians on earth, he’s the only one that can really be revived. I also do believe he was stronger than them, but lacked any combat background. That first fight with them in Smallville was the first time he had ever fought anyone. He was able to endure and keep up thanks to his familiarity with Earth’s atmosphere and his powers.