Take a control sample from your spinning

Somewhere not too far from when you start spinning, pull a decent length thread from your bobbin and fold it in half to get a 2-ply yarn, or in thirds to get a 3ply. Tie a knot in the top of that, then untwist just above it so you can take that strand out. Splice your yarn back together and continue spinning.

Refer to this sample to remind you what you are aiming at while spinning, and later to match your plying angle to get a balanced yarn at the end.

Tie the control sample to an index card, where you write any wheel settings, what the fibre is and anything else you want to keep track of.