If that was the last time you took any of them then you should not have an issue on the 12th, especially if you do not take them alot as in most cases 72 hours is the usual time frame for barbituates like this. Drinking alot of water is also the very best way of flushing chemicals from your system. The activated charcoal is a help but most of your test clean products all state drinking with alot ot water as that is the key to flushing your system. I am going to include a link below that has a chart that can also help you to understand how the amount of medications stay into your system. Once you click on the weight, sex, you also want to click the date of the test and the drug class as Barbituates and then scroll way down past all the cleansers they are suggesting you buy and it will show you the time framing of the class of drugs you have taken. I am not recommending any of their products just giving you a chart for reference as the main thing is timing and alot of water. The more water you drink the faster you flush chemicals from your system.
How Long Drugs Stay In Your System