The issue is that they've definitely teased it out at least one episode too many, so it feels like the reveal at least needs to be a good "a-ha" moment to be worth the wait.
Realistically, the Jack/main villain end of things doesn't matter, in the same sort of way that in The Avengers, the main payoff was bringing the group together; it didn't really matter that they were fighting cardboard villains.
But this seems like a bad example of the intended three-act structure. By the end of the second act, you should know what the stakes are. This would be like waiting to pull out "I am your father" until ROTJ.