Hi Danny,
I installed aligned and drilled the vertical and horizontal stab, installed and finished the rear fiberglass saddle and then started on the vertical and horizontal stab with the parts still on the fuselage.
I found it easy to work on the parts in situ as mine was a tail dragger so I could easily reach the fairings on the vertical and horizontal stabs.
For the wings, I installed, aligned and drilled the rear spar, then the front fuel support brackets, trimmed flaps as necessary, removed flaps, then removed wings to a cradle and installed the wing tips and strobes. I found it quite easy working on the wing tips with the wings in the cradle.
This worked for me and I can think of no negatives of doing it now before the fuselage is complete.
Cheers