I had major back surgery on january 6 the replace three disc and spinal fusion I'm doing pt how long will it take for me to get my energy back?

Back surgery. This answer depends on many factors. Your doctor is the one that knows your exact situation and can answer your questions.
Usually fusion is. . ...Not done along with disk replacement. It sort of defeats the purpose of disk replacement, having a fusion. One is 2 relive pain yet retaining motion while a fusion is done 4 pain by making the spinal segments fused from any motion at all.