The only specification for Service Charlie chevron placement that Ive been able to find is "4 inches down and centered." When the short sleeve is pressed, the pressed crease is not centered on the yoke at the top of the shoulder. Its a little bit in front. (the yoke is those two seams that run into the shoulder from the back and the neck).

On the Service B shirt, the pressed crease does end up perfectly centered on the yoke, making chevron placement simple.

On the C shirt, does the chevron get sewn with the tip of the chevron centered on the shoulder crease, or is it sewn centered on the shoulder yoke with the tip slightly behind the crease?

From the order:
"...will be worn single point up, centered on the outer half of each sleeve." and "On short sleeve khaki shirts, insignia will be centered between the shoulder seam and the
bottom edge of the sleeve (men)...".

Unless the cleaners really screwed up the crease pressed on the sleeve, go with the chevron centered on the crease. The yoke seam may not always be lined up with the center line of the outer half of the sleeve. If the really did screw up the pressing( angled/off center), have them re-press the sleeves before getting the chevrons sewn on.