Yes, definitely get the geometry sorted out before you start shaping the neck and peghead. Square edges are your friend

My comments above were in reference to the neck BLANK. I just wanted to point out that you have some room to adjust your blank as you are laying it out and fitting it to the body. This is something that is not inherently obvious. It is nice for anyone new to this, who might be reading, to have it pointed out. It may save someone from scrapping a mis-cut neck blank that could be saved. I think once you do a couple necks, the moving nut become second nature, so much so that no one really mentions it.