It took 8 weeks to get my first AF post pill and then the next was 6 weeks before they settled into a 5 week cycle.
It also took me 12 months all up of TTC with an early loss to conceive my first child.

Some fall into a regular 28 day cycle but because you don't doesn't mean you need to be treated with fertility drugs straight away. They can have some rather serious side effects so shouldn't be taken unless really necessary.