When to start the pill

Hi girls. Ive just had my iud out This week due to some problems and reluctantly I'm starting the pill. My Dr said I could take it straight away (wednesday) and that I'd probably have a funny period, and it may mess my cycle dates up a bit. I decided since my period is due next week to abstain from sex and start the pill next cycle. Only I'm not sure when I should be taking it. I've always been told that your heaviest day is CD1 but my period will probably go Like this mknday- spotting... Tuesday and wednesday- light bleeding... Thursday- medium bleeding... Friday and saturday- heaviest... Sunday- light bleeding.. done. So which day should I start the pill? I wish I'd asked the dr