So basically I'm wondering when the heck I'm gonna get the mission where Danse takes you up aboard that blimp. Cuz I've done the mission for Danse where I find out what happened to the other guys of the brotherhood. And have also done 3 or 4 quests each for Knight Rhys & Scribe Haylen but still not getting the blimp mission. Is it supposed to take this long? Or am I doing something wrong?

Did you progress in the MQ? As in: Have you killed the guy who killed your wife?

Edit- Anyway, you have to progress the main quest until the blimp shows up. After that, Danse will tell you it's time to meet the Elder and you get flown to the airship.

Are you talking about lost patrols quest? You need to talk to Kells. Here is the wiki http://fallout.wikia.com/wiki/The_Lost_Patrol.

Cheers,

-Klevs