Is it better to prepone or postpone your period with hormonal birth control? which way is the safest and most effective way?

Long term plan: Trying to change the date of your period with hormonal birth control takes long term planning. New oral contraceptive takes 10 days to be effective and up to 6 months to regulate a period. You should start oral contraceptives on the first day of your period, or on any day where you have a negative pregnancy test. The first 21 days have hormone, the last 7 days will be your period.