One joint if you are clean to start with will stay in your system for 3-5 days. Smoke again within that time and double the amount of time it takes to get out of your system So a joint one day and another two days later will probably take a week to get out. Smoke another in a few days and you are looking at two weeks.i RJ. Yes, you should be OK for one time ingestion of marijuana 10 days before a drug screen. In other words, THC is usually detectable for 3-4 days after one time use….and 10 days after you eat marijuana is a long enough time for THC to clear the system.