Preorders are already up for Nova Covert Ops https://us.battle.net/shop/en/product/starcraft-ii-nova-covert-ops
You get a discount and like a portrait or whatever. I'm not the biggest fan of game preorders these days with how many buggy games have been shoveled out by some companies, but Starcraft 2 has always been quality IMO. Plus it's unclear if you'll always get the discount for buying all three packs at once or if it's only a preorder thing. Personally I said, "shut up and take my money" and that's that.