I posted a thread about our girl when I was confused about the pre/post ovi shed. This girl looked like she ovulated while in blue but it was building (thanks freakie frog). After she shed we paired her with a male again and they locked, so it wasn't ovulation, that was her pre-ovulation shed. Now she is in blue again and I can definitely feel large marshmallows when I palpated her the other day (4 or 5). As far as a time line, it depends on the female. She had her pre-ovulation shed on 6/20 and, like I mentioned, she is in blue again (but we haven't noticed an ovulation yet). lol, its enough to drive you crazy! Keep pairing them as long as they are in good condition and you notice a definite ovulation.
http://ball-pythons.net/forums/showthread.php?t=94457