I got my hair cut yesterday.
There was only 1 person working at the time and the 2nd person they sent, their electricity wasn't working so it was still 1 person when I left.
I had to wait about 30-45 minutes on a wierd family that had 3 people get their hair cut.
There are no appointments, 1st come, 1st served. You keep track of it yourselves. It's the cheapest haircut you'll get at WDW.
Go right at 9 when they open and the lines shouldn't be too long, but you'll have to live with hair on you for the rest of the day.