Small Thrip infestation caught early. Enlighten me please

So I've been having small spotting on the bottom leaves of some very young clones I've been watching closely the past couple days and tonight decided to bust out the 100x microscope to get a closer look not being able to see anything with my naked eye and low and behold little tiny I mean really tiny white slugs. After looking around I'm 100% sure these are Thrips. I pulled leaves off multiple plants in close proximity to eachother and could only find them on two of my plants in veg.

I mixed up a fresh batch of Azamax and gave every plant in my veg a good dousing.

I'm wondering if anyone who has experience with these little buggers could give me some insite into what I should be doing over the next month or so to make sure I don't get an infestation. I'm not 100% sure how effecting Azamax/Azatrol is against these little buggers and the damage is very minute. I had a total of 3 leaves with them between the two plants but the plants are in close proximity.

Do I need to treat my soil with a drench or any other precuasions? I did make sure to give the top of my pots a good spraying with Azamax but didn't prepair a drench.

I do believe they can live in the soil. I've had them almost everytime lately.. they're annoying more so than anything. I bought a common pesticide spray at my local grow shop. It works, but like spider mites, in my opinion u have to just keep up on them.
I'm pretty sure they do live in the soil. I think store bought potting mixes often contain thrips. Kinda like gnats.
If they get bad they can mess up the plants... they bite the leaves and suck the juices/nutes out.
They can end up in your bud too, effecting taste and staining/spotting up any leaves they bite

I've kinda removed a bit of soil from the top of plant's container and replaced it to contro them in the past.

I was told spinosad kills them. If I spelled that right.