I wear earplugs all the time!!!
I put them in as soon as I arrive at the venue, and only take them out for sound check, when I need to make adjustments to the sound, or if I need to correct any issues (feedback, sources of him, etc.)
Prolonged exposure to moderately high SPL is just as damaging as shorter periods of exposure to higher SPLs.
Luckily, all the venues I work at are smoke-free indoors, but you work long enough in the music biz, you will encounter smoking venues.
I also eat as best as I can, and I pack healthy snacks for the gig to head off the temptation of bar food, and many nights, I don’t even touch a drink! I’m hardly a teetotaler, but it does make a HUGE difference in how you feel before, during, and after the gig when you stay off the sauce.