I spun this far:
And then this happened:
I was expecting it due to my uneven division of the braid, but I wasn't really looking forward to this part. I probably should have fixed the uneven divide earlier - joining while spinning would have been much easier than dividing the energetic single that's on the bobbin! I think I will wind the end connected to the wheel onto a new bobbin until they're about even in weight (assuming the bobbins are approximately the same weight and the singles are even enough that approximately the same weight gives me approximately the same yardage...), then cut the single and wind the first bit back onto another bobbin so I can leave it attached to the wheel, then join the cut end on the original bobbin and keep plying. Luckily I have six bobbins so the game of musical bobbins isn't a problem!