How to adjust roller rockers w/ hydraulic cam. First start up.

You can successfully adjust them pumped up or not: I prefer to do it not pumped up so I can see each lifter's piston compress, but have done it after being pumped up too.
The point is to put the lifters on the base circle of the cam lobe, find zero lash and then turn the adjuster for the desired compression of the piston.

OP, check the thread pitch on your adjusters, divide that number into 1 and you'll get .050" per turn for a 20 TPI. adjuster or .041" per turn for a 24 TPI adjuster. Use that to figure out how much to turn the adjusters from zero lash. For example. a .030" desired preload with a 24 TPI adjuster would mean 3/4 turn on the adjuster from 0 lash.