As an aircraft mechanic I've done lots of these, the publication AC 43.13-1b outlines the correct procedure. The test is done on a warm engine and, to start the test, air is introduced into the cylinder while the piston approaches TDC and is finalized with the piston at TDC. The airplane has an advantage because of the prop, you can grab a prop blade and manipulate the piston position instead of just parking it at TDC. This assures that the ring is fully seated against to bottom of the ring land.