Committing to drinking plan

I’m finding I’m having trouble committing to what my plan should be for drinking prior to social events. My mind likes to know the exact situation (i.e. who will be there, how will I feel at that moment, what emotions will I be feeling) before deciding my drink plan—which is clearly not possible. I’m stuck in indecision to decide what my drinking plan should be and ruminating about it for a lot of time prior. Any suggestions?