Finishing before cutting joinery?

So I'm building a table similar to this Four Eyes design. The legs are assembled and the top is cut to size. I'm thinking about spraying finish before cutting the final domino shapes for the standoffs between the legs and top.

Any reason I shouldn't do this? Seems like it would be easier to cut them after finishing, so I don't have to mask it off, and I can just expose unfinished wood for the glue up.