I had just turned eighteen a few months before and was in my first year of university/college. It was pouring down with rain and the curtains were open and the whole room was bathed in a blue-ish light from the storm outside, and I told her I was ready and things went from there
I don't regret it, but I didn't particularly enjoy it sexually very much. It took me a few more times before I actually started to enjoy it at all.