You are right, put weight on it then drive it around the block to settle in the suspension.
Measure from wherever is easy, as long as it is the same spot side to side. Count the turns of your track bar and write it down. Another spin and recheck. It might take a few times.
In the shop we have slip plates under the wheels so we don't have to settle the suspension after a adjustment.
If it needs any sort of adjusting you will have to center the steering wheel when done, with the drag link.
Most vehicles don't have axles centered but you don't really notice it until you install some larger tires. It really doesn't effect alignment or how they drive but if you are a little compulsive like me then it can be that one thing that just get you going.
2014 JKU, JKS lift,Poison spyder flares, bombshell covers,Rancho D2 control arms, JKS adjustable track bars, 35" Tires. GrabBars, Crawler Conceptz rear bumper, Smitty front bumper, Winch. Rough Country inner fenders, Teraflex Disco Mud Flaps
Backseat Dobermann Security