I agree with THUMPER....everything has its moments...and your moments of parents are coming 1st..(in a way)...when you know in your heart when the time is right...then thats it..the time is right...and so will she....take it step by step...but one word of advice...
KEEP THE LINES OF COMMUNICATION OPEN at all times...foundation is a good start and so is honesty...
prenup..sure why not? never hurts to discuse it with her..
congrats on being the before stages of being a dad....wow, look what you did
and its a good thing