You and your fiancee will have to decide the relative importance to you both to either have a “traditional wedding night” or to practice NFP so as to avoid pregnancy at this time. What you cannot do is to engage in marital relations (or in activities that prepare for marital relations) and then frustrate their purpose through the various forms of contraception (including coitus interruptus). If you and your fiancee decide that you need to avoid pregnancy right now, then you and she will either have to reschedule your wedding for her infertile period or find something else to do on your wedding night.
