There are various methods of checking dish. My favorite way is to reverse the wheel. Doesn't matter if it is on the bike or in a truing stand. I think tension has an impact on how many turns it takes to move it, maybe not. I started truing again after 30+ years of not doing it. Slow and easy is the trick, as mentioned. Being a bit of an engineer, I invested in a Park tension guage and found a Spin Doctor truing stand for $20. I don't trust my ear for making sure the spokes ring the same frequency to determine tension so the the tension guage works well for me.

It is intersting to see how far off spoke tension is even when a wheel is said to be true. It is from a rotational perspective but one spoke, or two can carry the load of a third one which is not tight enough.

The other trick in this kind of effort is to make sure the spokes seat. Some nipples that are rotated 1/8 or 1/4 turn are not set. You find out when you mount the wheel and there is popping for several rotations. Now the true may change. this can be avoided or minimalized by holding the rim in your hands at the 10:30 and 1:30 positions with the bottom of the wheel in your lap and use your elbows to push on the rim (Taco forces). Rotate the wheel and do it again until all the spokes seat. Check true again and adjust as needed. Repeat. This saves mounting the tire and wheel on the bike and then riding. Can you true with the tire in place? Sure, Let all the air out so the air presure doesn't add a variable.