Belgian yeast can be fickle. They don't always just rush through the fermentation. Some are, well, moody. You have to pay attention to them and not try to make them do something they don't want to do.
In almost all cases, you should let the temperature free rise to wherever it wants to go. That's a good reason for starting on the cool side. I find the strongest fermentations and best finishes come from not artificially constraining the temperature of the fermenter. Some of these yeasts will react quite negatively to trying to lower their temperature during fermentation.
Use all the proper tips for wort preparation (nutrients, oxygen, starter, proper pitch size) and the fermentation will generally be done in a week. If you aren't measuring gravity every day (and I don't) then it may not be obvious to you when fermentation is over; that could be where the professional quote comes from. I tend to let the beer go on the yeast a bit longer, until it flocs out, to give the yeast a chance to fully attenuate the wort and clean up after themselves.
To answer your original question, the temperature is the same in the wort and in the room when you pitch. As the yeast starts to work, the beer temperature will rise. Let it. You can move it to a warmer place if need be to have it finish, but I don't usually do that until it's done. It's more of a conditioning phase than a fermentation phase for me.
The only thing I would be fermenting warm would be saisons, which seem to require that temperature to get full attenuation. But I don't know what the other people are talking about. Chances are they haven't been to Belgium, and that they like their beer to give them headaches. High temperatures will give strong flavors. Wrong flavors, but strong. So if someone is impressed by intensity rather than character, they will likely be happy. But I'd rather get it right.
What yeast are you planning to use?