If you plan to become pregnant in the near future, but still use hormonal contraception methods, you should discontinue using them sooner rather than later, to give your body enough time to adjust your hormonal balance and thus prepare optimally for a pregnancy.
It takes the female body some time after quitting the pill to return to a regular cycle. Some women already ovulate in the next cycle, others may have some cycles without a fertile egg. It always depends on the woman, her body and the chemical composition of the pill. Therefore, it is not entirely accurate to say that with pill XY it would take exactly so and so many cycles for everything to return to normal.
Chemically speaking, most modern anti-baby-pills are combination products that not only suppress ovulation by inhibiting follicular maturation but also keep the consistency of the cervical mucus viscous and reduce the mobility of the fallopian tubes, in order to make pregnancy unlikely. Artificial hormones are the main actors in this process. The “natural hormone show” could take some time to get started, especially if the pill is taken for a longer period of time. Yet it could also work out as soon as quitting the pill. Nevertheless, it is advisable to plan a time buffer to allow the menstrual cycle to settle.
It is also important to not let the possibility of it failing to immediately work get to your head. Remind yourself of the fact that your body has a lot of work to do in preparation for pregnancy. Grant yourself that time.