I'm in the same boat. I'm polishing, then sealing. Which is frustrating because I'm trying to keep the water out! But I want to put a fresh bead of sealant "AFTER" I polish.
I suppose it depends on what you're doing. I am in the middle of a shell of resto. So as I pull out a roof vent, for instance, I will polish around the opening, then seal in the new vent.
One note that may help you is... the only places that I have found need polishing before sealing is around the window tops, and the vertical seams. If you clean & polish those areas first, then seal them, then you can polish the rest later.
Hope that helps!