Spray the plant with
spinosad. Then do it again in 5 days. Then inspect the top of the leaves regularly with a magnifying glass and look for tiny little yellow worms with legs. They squirm and they will spin in circles if you disturb them. They're pretty easy to eradicate in veg, and
spinosad is cheap. Unlike most cannabis pests, you won't need two different modes of action for killing thrips. Just
spinosad.