Building both
I'm there right now and there are a number of little things you learn along the way that you can apply to the other wing. It's a bit cramped in the space I have, but it is going quite fast. Although fluting the ribs is tedious you get good at figuring out how and where to flute to flatten the section, saving a lot of time. I think it takes less than 10 minutes per rib to debur and flute.
It'll take about 8 hours to prep the ribs for painting and I did the ribs in two batches and it takes about 2 hours to prime each batch with two coats of primer.
When countersinking the nutplates on the spar be careful, clamp a backing plate with a hole to center the countersink bit. The bit will act like a router if it wanders. Also, get another #40 countersink bit, the tip snapped off on one of my holes and had to wait for another one.
I'm using a small palm size rechargeable Black and Decker screwdriver with a countersink bit to debur holes, much easier and faster than by hand. Less than a second of spin does it.