Should I sleep with my bi best friend?

My best friend and I have been friends for years and for a brief time have even dated and had the occasional hookup. But we've never gone all the way. At this moment we're both single. And whenever we get together there's this insane sexual attraction that has me wondering if we should give us another shot. The only problem is that I'm still a virgin and I don't quite know if now is the time to "seize the day"... Advice? Suggestions? Help?