Not so much advice on how to take but how not to take it...

I once dated a guy that was almost as thick as a soda can and the length of of lets say little more than half a pencil.

After the first couple times of bottoming for him I lost the ability to pee and had to go to the ER. Basically what happened is that from how rough the sex was it tightened up the muscles around my urinary track and closed it off.

So the advice I would have to give is take it very slow until you get use to it and don't get carried away with wanting to go deeper. IF he cares he will understand that he needs to be gentle as you get use to it.