I no longer have to join twice! Usually after starting/restarting Steam/SC, I would time out when trying to join the server. After the first time, I would be able to join and play normally until I had to restart again.
I know I wasn't the only one because Missy's did the same thing, too. When it would happen, sometimes you'd see the person joining/leaving (possibly multiple times?) on the log thingy up in the corner of the screen, but they wouldn't actually be in the game until they tried joining the second time.
The newest release seems to have fixed this for me