As always - check with doc...etc.
But everything i've read indicates if you are on pred for 5-7 days or more (esp at 40 mgs, which is a fair amount) that you need to taper. Based on a lot of common exchange here it seems like if your doc wants you off (as in: the pred will not be your primary course of treatment to gain remission) you just need to taper slowly enough to be safe. Not to avoid symptoms returning. Perhaps 10 mgs/week ok here?
Am not a doctor. Do not play one on tv.