He only lets his teeth work over that nipple for a couple of minutes before switching to the other one. No need to let that one feel left out. It too, only gets a couple of minutes of attention before he's moving back up to sink into her slowly, giving her time to get used to accommodating him.

There's a pause after he's fully in to give her a last bit of time to adjust before he's rolling his hips forwards. It starts out at a slow pace but doesn't take long to increase in pace and force as he makes sure to hit the best place inside every time.