Info on Flexeril / cyclobenzaprine? helpful hints?

Hello, friends!
New doctor started me on Flexeril / cyclobenzaprine. 5 mg 3x/daily for back pain / arthritis-autoimmune.

What do you all think that I, as a new patient to this med, need to know about it?

I haven't been taking it that way. So far, few side effects.
I'm wondering if I should be taking this all the time, or just when I feel like it would help.
I've been dealing with pain for 30+ years and pretty much have gotten out of the habit of taking pain meds routinely because of allergies, etc. Mostly used topical treatments for a little relief, and rarely "big guns" when excruciating.

THANK YOU