If you can to stop yourself at a beer or two, you should be fine...given you have average body weight.
When I practice at home, I never practice when drinking anything. The neurological processes required for learning are severely hindered by drugs (alcohol, pot, etc.). I learn all the material my band will be playing completely sober...and I learn it perfectly.
Then, when I rehearse with the band, each member brings a six pack of different types of beer...which makes things fun. When we rehearse, we gauge our performance level according to how much we consume...and how far into each set we are. We do this so that when we play out in bars, we don't destroy ourselves by drinking beer and not being accustomed to how it feels and affects our motor skills. Additionally, we play our most technical songs early in the night so that we aren't fighting our favorite libations.
It's manageable if you're wise about it. If you cannot possibly play accurately while consuming reasonable amounts of alcohol, then you shouldn't drink whatsoever.
Body weight, race, food consumption, drinking speed, alcohol %, and overall physical health are factors to consider. Some folks are lightweights and can't play after consuming a single beer. It varies.
I don't condemn it, nor do I condone it.
It is what it is.
You're the only one who can make the right choice.
