I plan on doing the Chimay Grande Reserve clone and it describes pitching yeast into the secondary 3-4 days before bottling. Further instructions say that stored at 60 degrees can help the beer mature for up to 10 years!
I've heard that champagne yeast is a good idea for bottle conditioning higher gravity beers. They say to pitch the yeast a few days before bottling to prevent the possibility of bottle bombs.
You want to make absolutely sure that the wort is fully fermented at the time of bottling - if there's any left that the conditioning yeast can eat, it will have done so by the time you get to bottling it. Then the priming sugar is the only thing left to eat, which produces the right level of carbonation for the measure.