That sounds like a good order to do things. Get your electronics wired enough to at least do some testing. When you start building the extruder, rig up some kind of temporary stand for it. Don't bolt it down to the x-axis until you are sure that the hot end extrudes easily. The extruder is one of the most tricky and unreliable parts of the reprap. Expect to be rebuilding it a couple of times before you get it just right. You can save yourself some hassle by extensively testing the hot end before you ever mount it and try to print.
