Looks like a very interesting and challenging project. Since you still have other veneer panels to cut, my suggestion would be to cut them slightly oversize, except where they must perfectly butt into original wood. I think it may be easier to cleanly cut the overhang at the front end and around the inletting, than to fit everything perfectly while clamping and gluing.
I have never worked with pre-glued veneer, so I would also want to do some research to find out if steaming would affect the glue bond. Before I saw that you were using a heat activated pre-glued veneer, my immediate thought was whether you would be better off with an epoxy, or some other wood glue that wouldn't be affected by steaming. Here again, I can't say if steaming will be necessary , or if the veneer is pliable enough to be wrapped around the radius of the wrist without steaming. Of course, the 300 degrees required to activate the glue should also immediately flash off any excess moisture in the veneer.... I think????
I wish you luck, because if this works out well, it could provide a viable option to restocking in some circumstances. Wish I could be more help, but without actual experience doing this, all I have are some random thoughts and considerations for you to chew on.