Whilst the instrument shown is a thing of beauty, you yourself tell it is not yet finished.
You are guilty of falling into the trap of "he who pays" rather than "the piper calling".
The customer should choose from your available stock or walk away.
if they commission from you they should wait until you are ready.
You sir are an artist in your own right, realise your worth.
Don't let yourself feel the pressures of workload, let the client wait, they will appreciate their purchase more for having it perfect than brining it back.