It was definitely soon. Firstly though, he braced an arm beside her and the other sort of lifted her hips higher. It pressed his cock deeper inside her. It didn't take much urging to begin thrusting - more like just the capacity to think about movement. If it weren't an automatic action, he'd probably have lost the capability to remember to breathe or let his heart beat. Lucky there really.
He made a low sound against her throat, completely focused hard, deep movements of hips. He really wasn't thinking about whether it would hurt her or break her... That could not be expressed enough.