I'll have to remember that trick. Thank you for posting it.
The way I have been doing it is take a sharp #2 pencil, and with the lathe running, take the pencil and draw on the end of the part until you find the center, then set your tool according to the small circle. I also will leave the tool just slightly below center then leave a small tit on the end. Then if I have a few diameters to turn, I will use that small tit as a reference point and draw the diameters, again with the lathe on to show where your rough cuts will be. It saves a lot of time from, having to stop and check every few cuts. Just add a 1/32" or so when you make a mark from the center tit.