My migraine clinic gave me samples of Nurtec and it worked about 85% of the time but only for relief of my VM symptoms. I get combination classical (icepick/lightning bolt) and VM.
Back to your question,
For me, taking as an abortive, I noticed a reduction of vestibular symptoms in 1-3 hours.
I found it stupidly, interesting but not surprising that the product’s inactive delivery system is basically a menthol, citrus-based sugar pill which elicited vertigo and headache symptoms for me. I mean, how dumb is the manufacturer? I get it, it tastes like a fruity mint and is a marketing ploy, but that composition can affect a lot of migraineurs.
I’ve used it once for VM relief and it either worked within 20 minutes or my symptoms subsided on their own in 20 minutes. I’m not sure which.