You should be fine taking it out of the fridge at that gravity. I did a diacetyl rest on an oktoberfest at 1.024 and the beer turned out great. I would keep it around 60 degrees until the fermentation is done, or close to done, then rack to a secondary to drop down to cold lagering temps for a few weeks. The warmer temperature is to help the yeast ferment faster, and consume the diacetyl in the process. If you keep them at the colder temperature, they won't consume the diacetyl and you'll end up with the buttery aroma and slick mouthfeel.