With opioids it is always best to start low and then take more later as needed, since they don't affect everyone the same (well that's a good idea with any new drug actually). And it's better/safer to take too little than too much (you can always take more but you can't undo it if you take too much).
Xananx is not an opioid, it is a benzodiazepine. So if you have only tried Xanax then you haven't tried any opioids.
Since you have no tolerance, I would start with 2 pills for a total of 10mg or 15mg of hydrocodone depending on which ones you take. See how that affects you and you can always take more next time, or you can take some more after a few hours if you're still not feeling much. Opioids can be very subtle and sometimes people new to them don't think they're working because they just make you feel content, comfortable and kinda warm and sleepy. Most people new to opioids use about 10-20mg of hydrocodone. But some people are going to be more sensitive to it and some are going to get little effects from it, it depends on your metabolism.
Also, you probably won't need to and (shouldn't) take enough for it to matter, but just so you know, you don't want to take more than about 3000mg APAP in 24 hrs, nor do you want to be taking very much APAP on a regular basis. And make sure you don't mix alcohol or Xanax/benzos with hydrocodone.