Just to be clear, the one I was referring to is the Competition Electronics Pro Chrono, not the Shooting Chrony by PACT. There may have been some confusion because I called it the "Pro Chrony" instead of Pro Chrono. The PACT version has the word "Chrony" featured prominently on it. I have no experience with that one.
I like to put mine on a camera tripod about 10-12 feet from the muzzle. Then set the rifle on the rest and turn the scope down to minimum power. You can usually see the sky screen rods on either side with the scope on low power. Then just aim for the middle. Also helps to have your Chrono aligned as straight as possible with the path of the bullet (but below it of course). Not that hard really.