There's definitely this socializing aspect to it. I'm not sure it absolutely has to be on a weekend. Research tends to show that turnout rates are a bit higher on weekends than they are during the week. But if you have a system where you have several days to have the opportunity to cast your vote, the time really isn't the most important issue.
You might consider changing it in general that if you decide that voting should be mandatory, then it should be made as easy as possible, and the weekend might be a bit easier, yes.