The important thing about Wii VC to Wii U VC discounts

Before and after you transfer from Wii to Wii U you can still buy Wii VC games and then they'll be offered at a discount on Wii U VC.

HOWEVER

If you buy on Wii U VC before Wii VC, there won't be any discount on Wii VC and you'll have to buy it at full price.

Here's one of the important things of note to Europeans:

Nintendo are offering 60 Hz versions of games on the Wii U VC but you don't have a choice to switch to 50 Hz. Therefore it would work better if you buy the 50 Hz game on Wii VC first and then later buy the discounted version on Wii U VC—that is, if you want a choice. Also, so far this only applies to NES and SNES games.

Then again, you really should be able to get every version of a VC game when you buy it whether it's 50 Hz, 60 Hz or even in a different language.