I booked my photographers two years before our wedding in April 10 and wedding isn't until June 2012. I booked Hair Marck 2011. And I'm planning on flowers within the next month. And we plan on booking the officiant once we confirm and pay the deposit with Disney.
I only booked everything 6 months out and was ok. I booked all of my first choices without any problems. On a side note I wasn't able to book any sooner because we only decided on a disney wedding a month before.