The obvious answer would be: sit back and bask in your glory. You may think that you have won the genetic race and are better off than most other men. You may think that the world of sex is yours for the taking. However, such is not always the case.
Many women will recoil in shock from the sight of such an impressive penis. Sure, it looks big and the very herald of untold pleasures. But no woman, especially not one who has never had the pleasure of such an encounter, can fully repress the suspicion that your size may be too big for her. Most women will be afraid that insertion would hurt and that subsequent sex would be a painful ride instead of a pleasure cruise. Anal sex will be completely out of the question, whereas oral sex will be an awkward proposition at best.
So what’s left? First and foremost: don’t jump her. At the moment when your penis springs into view, your partner is most likely both aroused and afraid, not to mention more than a bit curious about how it would feel (heck, it’s not everyday she comes upon such a fine specimen). So take it slowly. Don’t amplify her sense that things may take a wrong turn. Above all, don’t skip foreplay! I don’t know how you feel about foreplay, but in this case it’s your best friend. Foreplay will help you push her past fear and into pleasure.
Second: don’t slam it all in at once. This will surely hurt, even if the last time she was tight was five years and a couple of boyfriends ago. Jokes aside, take your time and slide only your head in at first. Keep going slowly until her body adjusts to your size and she can take your entire size in. Once you’re in don’t start slamming full tilt like there’s no tomorrow. She would certainly not appreciate it.