Yep, ivermectin in the fall for bots is best. Of course there are other parasites you'll need to treat for, and it is best to do fecal exams 4 times per year to determine which ones you want to treat for. Your vet will have more info on this for you, or you can check out the AAEP website recommendations!
For anyone who has been following the thread: Well, I had the vet come out today and take a look at Trigger. She doesn't think he has a bowed tendon but rather swelling from a bad cut he had gotten previously. So she is having me continue to give him penicillin, clean the cut, and bute him if he looks sore. Hopefully he'll be back to normal before winter break comes.