I think it only remains active in the body for One and a Half hours. Personally I wouldn't drink whilst MMS is active and if you are definitely going out and having a drink I would allow a few hours - so perhaps take it in the afternoon if you are going out in the evening. As for the question of if drink is okay or not --- you'll probably get a resounding 'no' from some people here... but its a matter of to what extent you are ill and the reasons you may be using MMS too.
If you are using MMS because you have say hepititas then drinking would be silly really.
If you have the odd couple of beers socialising each week and you are not ill, and your only concern may be if a beer is ok while MMS active - then it isn't wise of course. Someone else will give you better advice than me though :S
You will get good advice here - there are quite a few poeple that really know their stuff on this forum.
Can I ask - Why are you taking MMS?