So it appears I have fungus gnats 
. I’ve treated with foliar spray neem oil mixture and sprayed the soil. How often should I repeat? Also when should I put DE on the soil? Should I cover it or only put it in a circle around it?
With DE you want cover all the top soil in your pot. I’d reccomend a product called microbe lift. It has BTi. It’s a beneficial bacteria that kills the larvae and they are what do the damage to your roots . You can add it right into your feed water . Has no effect on the plant just the larvae . Get some yellow sticky traps for the adult gnats .
let them dry out and the gnats should go away… its the most effective way to get rid of them… you can also flush the soil with a 50/50 mix of peroxide and water… it will jack the microbial life in the soil but should do a number on thier larve… best thing though is to stop wattering for a few days and beyond if needed…
So do you apply theDE after every watering?
You can use hydrogen peroxide in your water, it kills the larve and turns into oxygen in the soil.@420ismyfriend told me about it.I did it and haven’t seen one since!
The DE doesn’t work when it’s wet, so after the top soil dries up I just rake the top to stir up the DE a bit.