Ignore the cretin above.....
Take your time, make sure you are both at ease and don't expect 'too much' so to speak. I can't really speak on behalf of women (obv) but so far I have had sex with two girls who were virgins and as long as your bf takes it slow, makes sure you are comfortable and as long as you are both ready/have lots of foreplay it shouldn't hurt much if at all
Oh and if your bf is a virgin as well he may need a little help 'getting it in' (sorry for the vulgar description) and also 'keeping it in' You know your body better than he does so just guide him. Also; remember to never put the condom on untill you are
seconds away from actual penetration. If he loses his erection whilst its on due to fumbling, not being able to get/keep it in, then make sure he puts another one on before he penetrates so that it fits correctly. (sorry for the vulgar description again, sometimes there is just no nice way of saying these things!)
On the other hand, just because you feel you are 'going to do this' don't feel under any pressure to actually go through with it, just have loads and loads of foreplay and you might enjoy that even more. Sex shouldn't ever be something you feel like you have to do just because you both agreed to it, if you don't feel like it when it comes to the crunch then don't do it, simple!
Finally; don't do ANYTHING penetrative without a condom whether he ejaculates or not.
(edit)....and ignore the cretin below