Neem oil question

Hey everyone, ive been 12/12 since august 12th on this plant here and buds started roughly on the 26th of august...im hopin to harvest somewhere between november 4th & november 18th...its planted in a 68 liter rubbermade tote...medium is promix (potting and seeding mix) with added vermiculite....I'm using 2 part nutrients made by dnf....dnf grow & dnf bloom, both products are a 2 part mixture...about a week ago i noticed small bugs on the soil surface that looked 2 be fungas gnats...some leafs also showed signs of spidermite damage...the plant still looks really healthy still and the buds are great looking...its an afghani kush sativa plant...ive been spraying a diluted solution of insecticidle soap on the soil every other day and so far have not seen any other fungas gnats...i am going to pick up soem neem oil on frieday and hope taht it will work better for me...even tho i allready have buds on the plant can i spray the whole plant with the neem oil just not trying to get the buds but lightly with possible overspray from the leafs...? when theres 7 to 9 possible weeks left befor harvest will i be safe to apply neem oil and how many days or weeks befor harvest should i stop applying neem oil...please help any adive is greatly appreciated also can i spray neem oil on the soil surface and on the pot? i have photos of the plant allready posted on my other thread in the harvesting and processing section thread titled ***harvest question***