Ordinarily, it's only possible for one character to get three pets each year: one from the classic Azeroth quests (Piglet's Collar, the Rat Cage, the Turtle Box, or the Snail Shell), one from the Outland quests (Elekk Training Collar, Egbert's Egg, Sleepy Willy, or Legs), and one from the Northrend quests (the Curious Wolvar Pup or the Curious Oracle Hatchling). But you know how in Mists of Pandaria all of the non-combat pets on your account will be shared amongst your characters? If you run a series of alts through the quests and pick different pets on each one, you'll have all the pets on all your characters once the Mists of Pandaria content patch hits (or, at the latest, once Mists itself does).
The tip was so brilliant that I slapped myself for not thinking of it, so I wanted to draw some attention to it here as quickly as possible. Pet hunters? Save yourselves four years' worth of waiting, and get cracking.
If this is your first year with the holiday and you need any help with the achievements, you can find our guide to Children's Week here.