I know you don't want criticism or questions, you want your question answered. However, everyone is right here. We don't know your specifics to give you a good answer. Also, as PDM said, I wouldn't want to be the one telling someone's daughter or son how to go about doing something like this and end up getting myself in legal problems.
If you know it's the right time, you'll work it out. No one can tell you how to go about it.
I know it's difficult to start though, especially when you're planning it. Me and mine waited until our wedding night which I can vouch for being the best path for us! But the oddest thing was talking about it. How do you start?
You need to talk to her because you need to know what she felt. I talked to many people before talking to my then fiancee, including my best friend's. The advice they gave me was good and fine, but something I would NEVER do in such a situation.
Talk to her. Think it through, be 100% sure and 100% safe.
