Dude you need to replan your brew day. That is a big-ass beer and you need to build up a starter to get enough yeast to pitch into that bad boy. Even better brew a Belgian ale something in the 1.045-1.050 starting gravity range and then use the yeast cake from that to pitch into your Rochefort 10 clone.
I usually start the smack pack first thing in the am and then pitch into a starter once it fills out. There isn't enough yeast in one smack pack to pitch adequately into a beer unless you are brewing about a 1.035-1.040 ale, and even then you are underpitching some.