It’s going to take more time than you think. Please plan for that.
Pad your time a little bit so that you don’t run into a crunch and the added stress that brings. Besides, if you get it done quicker, then it only exceeds expectations vs creating a situation where you disappoint someone, including yourself.
This is experience talking… learn from my past tendency to not allow enough “Yutori”. Consider those “spaces” to be just as important as the actual task at hand.