The choice is largely practical.
If you can't paint at home, chances are you'll fully assemble and paint later. And since very few airports (or T-hangar neighbors) want painting near other airplanes, you'll need to fly somewhere, probably to a hired gun. Which is fine. Painting is not for everyone.
I came out of the tube and fabric world, where airplanes are fully built, then completely disassembled for cover and paint, then re-assembled. Not surprisingly, I paint before going on the trailer. It's soooo easy to paint parts when they can be flipped and rolled on stands set to a suitable height, and lighting can be controlled.
Even if you assemble, fly, then paint, all the small parts and movable surfaces are coming back off anyway.
Delaying paint until after flight test doesn't have much merit. We're not building prototypes; RV assembly has nothing experimental enough to require airframe configuration changes. The "leaky tank rivet" comes up a lot, but as a practical matter, only the very worst will show themselves during the initial period. Many leaks don't appear until after G-loading. Blisters typically don't show up until after exposure to warm temperatures and G-loading...and of course require paint.
Carl is right; for sure paint the inside at home while it is bare. And yes, for interiors two-component paints are well worth the extra effort, single stage or clearcoated.
Build a few lights on stands. Place them so they light across the surface, and you'll be able to better see how the paint is hitting the part. And painting is a skill. Practice on an old fridge or Uncle Bob's rusty pickup truck before shooting your new airplane.