53 sounds good, and don't stress if its a few degrees higher or lower. You should first rehydrate the yeast in a sanitized dish, using sterile water (either distilled or boiled then cooled back down to room temp). Once hydrated cover the dish with a sanitized piece of foil and stick it in the area your using to ferment at 53. This will give the yeast time to acclimate to what the wort temperature will be. Ideally your yeast slurry and wort will be within a few degrees when you pitch.