Yeah, me and my friend spent a couple of games each playing the London trying to get it, and we didn't get it until a few hours later.
What are the requirements to get the opening book achievements?

if you look up the opening on Chess.com and use the sequence in bold at the top you get credit. you dont seem to get credit if you go in any other order
I finally got the badge!!!
...maybe it just needs some time? I dunno...