when you're ready for it, just do it ... forget the foreplay and get on with your business ... just so you can get a feel for how it's like ... i couldn't get it up for shit my first time and i always have problems with every girlfriend the FIRST time because I don't wanna suck ...

When you're ready, just do it ... then you'll, at least, have it in your head that it isn't your first time and you'll get more and more used to it ...

If you don't have a problem during oral, then when ur really "up", just take it out her mouth and well ... insert! haha

GOOD LUCK, DUDE!