Dumpster Diving Questions - Canada/Ontario/Mississauga

Hey, so I wanted to start dumpster diving because I'm trying to do carnivore but just cannot afford it. It seems like something in line with my morals and throwing food out seems plain wrong.

I've went today to a few grocery stores just to check things out, and figured out that the Loblaws near me has their dumpster unlocked and fully accessible, but it was unfortunately empty today (A Tuesday at approximately 2pm).

Does anyone have any tips for when to go to grocery stores (Day/Night/Time) ideally before perishable foods go bad? Should I go after they close? When does the garbage truck usually come?

I'm very new so any advice will probably help me a lot!

Also food doesn't have to be perishable since I end up giving away a lot of food I don't need to homeless people in my town.