When I got my .21 kit I just started taping pieces together to see how the fit was. Ed did a helluva job back then as the tape went to the side and the epoxy came out!
Start test fitting the bulkheads thne when you start gluing, go from back to front as you'll have to bend the top and bottom together at the front.
The sponsons are a little different from the norm but somewhat easy. You have to cut into the foam so that the square booms have a place to sit, probably the trickiest part of putting the whole thing together.
Anybody reading this and not know about the Hughey 'riggers might be wondering what we're typing about but you and I do.
If this is your first boat you might find it intimidating trying to get it going but stay at it.