Work Party Drinking Etiquette

I have a work party coming up and not sure if this is the right place for this but I'd like some thoughts. The place we are going to has particularly expensive drinks so some my coworkers and I were thinking of "pregaming" (for lack of better words) before the event. I'm 19 so just barely legal and all of my coworkers (including ones not planning on drinking before) are all very tightly knit. To get a better idea of the vibe of the company, we are all pretty outdoorsy and granola-ey and are very open about drinking, smoking and shrooms, and regularly have (non work official) bonfires together where we do just that. What is an acceptable level of drunk to get for this situation? I feel like it would be less appropriate if we were more corporate and strict but I don't want to over do it either. Any thoughts?

Edit for some context: I’m not planing on getting anywhere near drunk enough to make a fool of myself, that’s out of the question (although my managers usually have at least 2 fishbowl margaritas together). Second I work part time at a retail job so “career” is not really in my plan there Also the place we are going to is kind of like a board game restaurant rather than a fancy sit down restaurant so it’s going to be very relaxed and not super stuffy Another Edit for even more context: I am legal and I would not be driving