I'm sitting with a brand new one in for the first time right now, it was the small in the set of three but much larger than the one i have used before. Sir made me lube up a lot before he watched me pop it in and although it was a bit of a body shock at first its sitting pretty now, as i am! Take it slow, although I have had much experience of anal sex in the past I would never go into anything like this without the right preparation. I will say that the large of the set is bloody massive and i gulped when I saw it, i doubt I will ever take it but I am now in the right place to start to think about the medium, at the beginning with a lot of time and lube on my hands!
Good luck and above all else enjoy because it ain't worth doing unless you like it!
Gx