I worked for only about 2 hours on this mirror yesterday before heading off to substitute teach. I was very mindful of how I placed my pieces of handcut glass on this mirror as sometimes I would put them in places to cover up the scars on this mirror and not necessarily for aesthetic reasoning.
For example, as you can see, I put an almost perpendicular line of "vine" across the short end of the mirror that I was working on yesterday. This was very intentional as it followed the faint, but noticeable scarring caused by the electric sander that an unknown person had used on this very old mirror. (I found this mirror outside in the snow next to a garbage can in Minneapolis years ago. Hopefully this mirror will become "trash to treasure".)
Cutting and placing the glass will take many many hours. My estimate of my time to complete this mirror is another 20 hours of just placing the small glass pieces. However as I always seem to underestimate the needed time involved to complete anything, it will probably take 25 to 30 hours.