I confess I have no idea where my whizz wheel is. I go with IO540, though I always draw a line on my chart, take my 10nm thumb with me and a stop watch. I also note headings on my PLOG though not usually times since unless I loose all the electrics and the spare handheld GPS I've usually got that readily to hand.
Crude knowledge of the wind, drift angle and speed together with a 10 mile thumb will give you a quick approximation to times on the fly if push comes to shove anyway.