You will choose the workout your body needs. If you need to fix your abdomen separation, you will first work on that. If you need to strengthen your core and pelvic floor (stop leaking urine when you cough or jump), you will first work on that. If you do not have any separation or pelvic floor issues you can start with ‘back to fitness workout.

You can repeat each level until you feel confident, don’t see doming from your core, or pressure or bulging in the vagina, or leaking from the vagina or anus. Always work within your threshold, but keep progressing and challenging yourself. 

So you could take anything between 8 weeks to 12 weeks to do this program or sometimes even more. Self-pace it, but do it CONSISTENTLY.