How long would it take for drugs to get into your system? say you have a drug test in 8 hours 12 hours or 16 hours, if you do a drug 8 hours before you take the drug test will you test positive for it? say oxycodone for example , does it turn your piss immediately positive if you do some? or does it take a day or so to get into your urine? just wondering cuz swim just came up on some candy , and hes really itchin to do some.