MrStinkyanswered grow question 3 years ago As The8th said - I'd go for nematodes straiight away, theyd be with you before the weekend but do take a few days to kick into action, should be cleared up by next weekend, make sure you buy the right species, I had fungus gnats that nematodes got rid of in a few days.
You could try hydrogen peroxide root drench (opinions vary regarding % solution) but vinegar is very acidic so best to check your soil pH quick to make sure you havent just gone scorched earth on your plants and if its way too low get it flushed.