I took 3 xanax (alprazolam) tues when should i be able to give a clean urine screen?

Depends: Xanax (alprazolam) comes in 0.25, 0.5, 1 mg and even higher doses, and has a continuous release form. If these were prescribed for you for anxiety, you only need to have the prescription. If they were not prescribed, and you are being monitored for some condition for which you should not be taking benzodiazepines you would be better off concerned about having a drug problem and seeking help. Could be 3-5days