Your vet and the Stud owner should both be able to help guide you on this. Generally progesterone testing should begin between day 7-9 of the cycle and it's typical to test every other day (sometimes every 3rd day depending on numbers) to find BOTH the initial rise (2-3) and ovulation (>5). Finding the initial rise (which roughly correlates to the LH peak) allows better planning for when to ship. But you still need to continue testing to confirm that ovulation occurred.