If I interpret what you're saying correctly, active fermentation started within a day of pitching. With the temp profile you used (start warm, wait for signs of fermentation, then drop temps), there's a pretty good chance diacetyl was made. Often people will do a d-rest without even tasting, just for insurance. I'd say that since you've had 14 days of fermentation it's not unlikely you've already reached your expected FG. But you should still taste and measure SG to see where things are. If you haven't reached FG, there's no need to drop the temp back to 50. Just leave it at the d-rest temp till it hits FG. You definitely should wait till the beer reaches FG (or reasonably close to it), before dropping to lagering temps.