Has Nintendo said anything about how large the downloads for these games will be?

The reason I ask is that the 3DS came with a 2GB SD card, and I want to know if I should get around to getting another bigger one.

Definitely under a gig. If not, SD cards are extremely cheap so you can easily get a bigger one. The actual file size probably won't be known until the day of release.

I still want the hard copy. Especially for Nintendo games that seem to hold value pretty well.

the size of New Super Mario Bros. 2 is 370 MB (2,950 blocks)

Source

I'm more curious at what time it'll be available... cause if it's going to be like PSN where it sometimes doesn't update till like 9 at night then I'll just run to the store.

@awadnin said:

the size of New Super Mario Bros. 2 is 370 MB (2,950 blocks)

Source

They're still using blocks? Shit.

@BlatantNinja23 said:

I'm more curious at what time it'll be available... cause if it's going to be like PSN where it sometimes doesn't update till like 9 at night then I'll just run to the store.

Nintendo said the game will be available at Midnight to download.

http://mynintendonews.com/2012/08/12/new-super-mario-bros-2-download-to-be-released-at-midnight/