According to Jamil and Chris Whites book "Yeast", they say the most optimal temp is 68, and that its best to start at 65 for first 3 days since the fermentation process is most agressive during that time since the fermentation creates excessive heat during the multiplication phase. Starting at 65 should offset that heat generation. Then increase to 68 for most of the fermentation. Then finally, bump to 75+ for last 10-20% of fermentation. They mention that most of the fusel alchohols and off flavors are made during first stage of fermentation, at the end you are just trying to keep the yeast going and maximise attenuation.
The book describes that its best to judge your fermentation by gravity readings and not by the number of days. After the gravity has finished decreasing, the fermentation should be left for a few days to let the yeast clean up some of the residue fusel alchohols.
In my personal opinion, If that temp is the temp of your coldroom or whatever, I would just leave it to ferment at that temp until you are at about 80% of your final gravity. Then move the fermenter up to your main floor where it is warmer to finish fermentation to maximize attenuation.