The input-output relationships among the primary, secondary, tertiary and quaternary sectors of the U.S. economy offer some clues about the nature of the sectoral-structural problems.
In brief: Xanax. Hello. IF your liver metabolizes it normally, then xanax should start working within 60-120 minutes. You are very young. Xanax is not something that will be good for you to take long term. Xanax is in a class of medications (benzodiazepines) which are very addictive. It's worse when stacked with opioids (narcotics). Your generation, from the statistics, has the highest risks. Avoid the risks.
To answer your question 15-20 min you will begin to feel effects. Although it is concerning you mention a 5mg Xanax pill, Xanax only comes in .25mg, .5 mg 1mg and 2mg pills. All would take effect around the same time period though and last approximately 4 hours depending on tolerance.