Thc oral test 10/Ng ml

Hello how much time should i wait before driving to pass an eventual roadside oral test? In my country Police can drug test you Just like alchool and i want tò be 100% sure that im passing an eventual oral test before driving again since i dont need the car for going to work. The cut off of the tests its 10 Ng/ml for THC but of i get tò 0 its even Better since i dont want any risk.

I smoked hashish for 4 days 4-5 spliffs a day but i havent smoked for 3 months before.