I started back on Vitamin-D and Omega-3 (with extra EPA & DHA) about 2 months ago or so. Sadly, I don't feel much of a difference, but I believe the potential harms are quite minimal, so I am going to maintain supplementation for the purposes of self-experimentation.
It took me more than 3 months to get to the lower edge of the desired range with my blood level on about 8000 UI daily. There was no instant improvement, it takes time.