I understand your concerns.
to prepone your periods may not always give you the anticipated results.
Instead of preponing your period, I adivise you to postpone them. After completing the 21 day pack of femilon, start the new pack the following day without any gap. Continue to take the pill until all the functions at home are over. Once you are free you can stop the pills. You will get your period in 3-4 days time ( within a week).
I hope I have answered to your satisfaction.