I've woven the first few inches of my 3D piece - one of the soft-coloured ends with just a hint of the colours to come. On my PC screen, this appears almost to size, though the colours seem changed a little as is so often the case.
I'm weaving intuitively as I always do, treating the warp bed like a canvas to be painted upon and stitched into and taken out and changed and rewoven if the balance seems wrong.
So this is not set in stone and may change as I progress. Perhaps this is a lazy way to weave and I should plan all before I begin, but planning in detail seems constricting and limiting and contrary to my instincts.