The problem with using calendars is actually you're pretty flexible about when you want to get most stuff done, you just have a deadline. But you don't want to do it at the last minute, so for a weekend task you want to check in a few times to see if you are not too busy to do it.

http://www.dueapp lets you put a time to be reminded and that has really clear snooze functionality. So I procrastinate a lot (snooze) but I'm always aware of it in case I have a deadline, and I don't have to worry about remember it.

(I'm unaffiliated with Due I just love the product)