If you mean that you are relying on taking your temperature to know when fertility returns, it will only tell you that in hindsight—ie, that ovulation already occurred. To know you are fertile on any given day, the woman must observe for the presence or absence of mucus.
Regarding the timing of the return of fertility, it can take months for fertility to return, or it could be imminent. In general, I would suggest pumping is probably not going to be as effective at delaying the return of fertility as nursing at the breast, but what is generally true is only minimally helpful, as the important point is that how soon fertility returns varies, and so the key is for the woman to observe the characteristics of the cervical mucus to know on any given day if she is fertile or infertile.
Hope this helps increase your understanding of the effect of breastfeeding, whether pumping or not, on the return of fertility. For specifics, it is best to contact an NFP teacher for guidance in accurately interpreting YOUR fertility.
Sheila St. John