Hi Christine =)
Technically, no you don't have to start your pill when your period starts. Here are different suggestion start dates.
** First approach: Start your first pack of pills on the day your period begins.
** Second approach: Start your first pack on the first Sunday after your period begins. This will result in your menses almost always beginning on a Tuesday or Wednesday every 4 weeks
** Third approach: Start your first pack on the fifth day after your period begins.
** Fourth approach: Start your pill today if there is absolutely no chance that you could be pregnant. Use a backup method of contraception until your first period.
Because you say your taking the pills to help treat acne then you can by all means start whenever you'd like. Just expect that there will be a possibility that you will have a strange period or lots of spotting. If you do choose to start 'today' and end up engaging in sexual intercourse then be sure to use a condom or some back up form of contraceptive. Hope this helped.