I think my Model B took closer to a minute to fully boot and start my Pd patch.
The Model 2 seems a little faster, maybe 30 seconds or less, but unfortunately I don't think an almost instant boot time is realistic (I would LOVE to be proven wrong on this). It's definitely one of the more frustrating things, if you want to use the Pi at a gig or something. Then again, it could be a lot worse.
The determining factors will probably be what distro you're using, and how many services have to be started up at the very beginning.