Can you give matanos l’evyonim before Purim? Shalach Manos? on the Night of Purim?
Mishloach Manos is a Purim-day mitzvah. There's talk about asking a proxy in advance to deliver them on Purim day for you, which should probably be okay.
Matanos L'Evyonim should either:
You're not supposed to give matanaos l'evyonim too long before Purim, as the poor person may have already consumed the gift by the time Purim comes around. (And if someone is struggling, to hand them a large check and say "you can't use this until next week!" shows you're missing the point.)
Similarly, "if you look around on Purim day and there are no poor people in the town", you can either set aside the money on Purim day, to use later; or mail the money on Purim day.
So if your synagogue has a collection a few days before Purim (or Purim night) that will be distributed on Purim day, that's fine.