Your ankle flexion will improve, adding spring to your stride in a short time. However, be cautious before going out and attacking Mount Washington. Do a similar cooldown and ice any sore or tender spots. Running hills takes some getting used to and can result in soreness, and even injury, if you aren't conservative as you begin this new activity. If possible, run on softer surfaces than roads.
Grassy hills are ideal as they provide more cushioning.
Be wary of slippery conditions, hidden holes or other nasty surprises. Runing down too quickly could injure your quads as they are the muscles that absorb most of the pounding. This is meant to be the recovery phase, so ease up. Separate workouts to improve your downhill running can be incorporated into your total training program. In these separate sessions, learn to run at an accelerated pace downhill.