No please, don't make it a one day when you must show up.
As someone from argentina, the idea of having to go to voting one day, and because of bureaucracy the voting process is slow, and ugly, and tedious. It won't work.
Also, having to vote leaves to the idea of politicias buying votes, and saying things like "if you don't vote for me, we'll now and we'll kill you" (wich is a real thing because people are ignorant and think the vote is not a secret, or are paranoid about it)
So no, the "you must vote, and the voting period is just one day" it's a horrible, horrible idea.
Even if it's done on schools on sunday, it's horrible.