Just a reminder that you can opt-in to have your stud be breedable to FF-owned mares on his stud settings (via Edit Horse Information on his page).
You won’t get paid anything for the breedings, and you won’t be able to pick which specific mare(s) gets bred to your stud.
However, you will get more foals on the ground, and FF mares get bred after each breeding slot ends. (So if you have your Feb slots fully booked, but then someone doesn’t end up using a slot at the last minute, a FF mare would be bred in that slot, but it doesn’t prevent you from fully booking your stud first.) Mares are chosen in order of performance (high-ranked or well-raced mares first), so the chances of getting a nice mare for your stud are pretty high. 
No need to opt-in, but if you want more babies to your boys, feel free. You can opt in at any time, but the first auto-breeding will happen on February 22 (for the Feb 15-21 spots).