By the time the temp rises, the egg is already gone. (I understand that is not what you're asking me but just want to make sure you know that.)
The problem is that things change with your patterns. They do not always hold steady month by month and so what happens in one month may not help you know what will happen in the future. It is worth a try (but you'll have to wait till you are several months postpartum to try it, of course) just don't count on that it will always stay the same every month that passes by.

