I found a Shar Jorgenson template/directions for Apple Core at the Goodwill about a month ago. Bought the template to use in the "someday" future, most likely with my homespun plaids.
I haven't done one before but I have done several drunkard's path variations as well as fan quilts. Similar to what QuiltE said, for me it works best to finger press the center line and then sew/pin out from it, depending on the size that might mean I actually sew it from the center twice (once in each direction), other times I do it in a single curve.
Here's the link to the template -- it includes a how to video on Shar's method (which apparently uses a glue stick instead of pins!):
https://qheartland.com/collections/t...e-template-set