It took a while for me, like around the same time it takes points to show up on my account. The GCs showed up on the Purchases tab of my account right away though.
I just tested this out with the Battlefront II bundle (the regular PS4 Pro is out of stock online), and it doesn't work. "Playstation 4" means the entire catalog of consoles I guess.
Went to 2 Office Max/Depots and called another 2. All places didn't have GS gift cards or ran out. I'm going to try another one later tonight, but I don't think I'll be able to get a PS4 Pro at the lowest possible price.
Not listed, but then again, I'm not sure if what I have access to is the whole list. Most likely though. Some of the newer releases like Wolfenstein 2 and Evil Within are more expensive even with GCU.
I got the early access e-mail as well.
PS4 Pro is $350 and comes with Destiny 2 (not the bundle). Some of the game deals are the same, but many are not as good as well. GCU works though.