From my experience, the first time you try it, 3 months. Then each time it goes farther. Indefinitely e.g. years! It will NOT affect your future fertility.

A good read is John Rock’s Error by Malcolm Gladwell on how it’s not necessary to have a period while on the pill. The withdrawal bleed was just put there because one of the creators of the pill was a devout Catholic and wanted to use the pill with the rhythm method.