I had a spinal fusion and decompression on December 7 2016 and I am going back to work April 4, is This too soon I feel pretty good sometime and somet?

Precautions. If you have heavy physical responsibilities, a work hardening program is suggested, but if you do office work, likely you could return with periodic breaks.
Followup. You would need to have followup and discuss directly with your surgeon. At issue is whether your fusion has healed solidly, how the strength in your back muscles has returned, and finally the nature of your job itself. I usually let my patients return to restricted jobs 4-6 weeks post op and full duty 8-12 weeks if otherwise doing well. Discuss with your surgeon.
It's up 2 Ur surgeon. Only he/her can advise you. It depends on many factors,how the fusion is progressing, what type of work you do. So after a fusion I would let people return 2 a desk job earlier than a laborer.