There are two issues that I see. One, the front to rear spar spacing is pretty critical and two, the spars must be match drilled to the center fuse bulkheads. I think you will need to have the center bulkheads drilled to the spars before you start on the fuse. Therefore you will need to pay for the wings and fuse at the same time because they match drill the bulkheads to the spar before they assemble the wings. The front to rear spar spacing is a different issue, and I can only speak for the QB wings because that is the path I chose. Assuming you order the wings and fuse at the same time, you can do nearly everything without the wings while the factory assembles the wings. However, there is a risk that the front to rear spar spacing will be incorrect. You have about a 1/8" window to work with (+ - 1/16") for front to rear spar spacing. I built my fuse to the plans and the wings fit perfectly when I got them. I can also tell you that I was very stressed about them fitting for the entire build. I rolled the dice and got lucky.