Are you skinning it and mounting it? Telling the quality of the bird from the feathers alone is really an impossible indicator to the quality of the bird for mounting. The feather will last forever. The skin will dry out or burn over time, but in a freezer bag with the air out of it, the bird will be fine. If you are mounting it, but don't have the time, at least skin it, and freeze it in water. They will last an eternity. I just mounted an eider a week ago that was shot in January 2005. It was skinned, fleshed (not needed) and washed (again not needed, but what the hell), and frozen in a block of ice. the bird was as supple as the day it was skinned, and mounted up just fine. If you are getting it done by another taxidermist, I would get it to him. They will typically be fine in a freezer bag for quite some time, provided it is wrapped very well, the air is squeezed out, and the freezer is not a frost free freezer, but why wait?
Good question, probably only asked 153 times? lol