Find the Centershot of your compound bow.

the idea is actually from a YouTube video, where someone suggested to use 2 allen wrenches for the same purpose. I refined it.

This will only work, if your bows cams are not offset, but are aligned with the center of your limbs.

How to use:
remove front stabilizer and sight from your bow. Put it upright and level (stand or vise).
Nock an arrow.
Put one of the pins into your top and bottom limb screws (yes, you'll need to print 2 of them) and run a piece of thread around them as shown in the picture (I'm using serving material for this).

Your arrow should be between the 2 strands of the thread. Now you can measure the distance from each strand to your arrow (or just eyeball it). Adjust your rest, until it is equidistant to both sides and you're in the ballpark. From there you may shoot it through paper or do walk back tuning to dial it in.

There's 2 versions: 1/4" for most bows like Hoyt etc. and 7/32" for some brands with smaller Screws.