My psychiatrist prescribes me anxiety meds (and he is VERY strict about amounts; like for me personally for my symptoms I got maybe 7 pills for a month). I never really used them because I didn't know where the line was between needing it or not. I addressed my concerns to him and this is what he told me.

No one can tell you when to take the medicine, but don't be afraid to take it. That's what it is there for. If you feel your ability to cope with the anxiety is too much, a panic attack happens, or something of that sort-- take it. If you think you can manage without-- it's best you don't. As long as you're not finding yourself taking it everyday, and discern if you're able to cope truly, you shouldn't obsess over if it's a right moment.

I personally like that advice, because anyone given an anxiolytic PRN has that concern, you're not alone in that. I'm not telling when or how to take your medicine of course, I'm not a doctor like you said, and more importantly I'm not YOUR doctor-- what's best for you is between you and him. But I think as a general rule that makes sense.

I hope I didn't overstep any boundaries by sharing the advice I received about it. It's one I live by.