About how long does it take for refrigerated challah to come to room temp?

to slightly speed up the process, you can divide your dough into equal-weight portions depending on your plait design (3, 4, 5 or 6-strand). I like to pre-form them to relax the gluten and make rolling easier: pat out each portion into a disc, then either fold down the edges and pinch/seal to make balls, or: start the process of rolling them into strandsw: fold over a bit of the top, fold in the sides, then continue rolling top down into a "sausage," sealing and pinching the edge at the final roll. Let them rest 10 minutes or so, then begin rolling and lengthening them on the board into the longer strands you'll use for plaiting. Pre-forming helps the gluten relax and and makes the final forming easier and will also aid in bringing them to room temp. vs. a larger mass of dough.Bear in mind the ambient temperature of the room, and adjust the resting time accordingly. Once you plait the challah or challot, you can give it the final rise.

Depending on temperatures of your fridge and room, about 1 to 2 hours.