So I took a look at a sample of 4 room server launches and I do see the 30 sec delay that you're referring to. I believe, however, that this isn't an issue with server launches taking too long... I believe the issue is that your lobby config is setup with an early launch window of 30 secs.
What the early launch window setting controls is at what point the "early" launch window opens. The early launch window is the 1st time that the matchmaking service will consider it appropriate to launch a server/container for the lobby members.
So what this means in your case is that the matchmaking service will NOT launch a server/container for the lobby instance until AT LEAST 30 secs has passed, regardless of whether or not the lobby members meet the launch criteria sooner than that (i.e. one of the members has set their "ready" status to true).
If you want to speed this up, I think you should look at reducing your early launch window setting.
Let me know if that makes sense or if I'm not understanding the issue correctly.
Thanks!