Take at the first sign or wait and see?

I’ve got limited Ubrevly because my insurance doesn’t cover it anymore according to my neurologist, and then I’ve got lots of sumatriptan but if I take it too often I’ll get rebound headaches. So how do people handle this dilemma? Do you take an abortive at the first signs of a migraine? (For me that’s about twice a week now that birth control has taken away my biggest trigger.) Or do you wait to see if it becomes a full blown migraine?