The "aperture plane"? You mean the one the exit pupil is in? Or the one the entrance pupil is in? Or where the physical diaphragm is?
None of the three is the correct thing to measure from.
You need to measure from the rear principal plane. Where that is located (and where the entrance and exit pupils are) depends on the lens design. When data are provided by the manufacturer, they usually state the position relative to other bits of the lens, like the last lens vertex. So you need to do some calculations (involving the exact focal length, not just the nominal focal length) to find a number you can use.
But that's all too technical. Not practical.
Cameras have a groundglass screen. Use your eyes.
Reduce the lens to film distance/bellows draw, until everything starts getting out of focus. Go back a bit, "et voila"! Infinity focus!