The debate is usually drop hop before or after cold crash...
+Before the beer is warmer and the dry hopping will go quicker and the cold crash will help the hops sink if they haven't yet.
+Dry Hop after cold crash there is less yeast for the hop to stick to and the dry hop will be "better". You can go as far as dry hop in the keg.
The main issue you will run into with dry hopping in cold beer is poor hop oil extraction. Your best bet is to dry hop at warmer temps to get the best yield, whether it be before or after your cold crash.