Here is a little pdf that may help you plan out your pairings by the calendar. You could select a pairing date and it would show you approximately when the pair would lay, have 28 day babies, lay again, etc. etc. It is extremely helpful when using it in reverse. If, say, you wanted to send a baby off to a one loft race or futurity on March 1, you could instantly see when to pair your birds in order to have 28 day babies on March 1.
Special nod to Flapdoodle of the Pigeon Talk forum who created the first one of these I used last year.