Install all wall cabinets
IF you can't get in there then either- screw from bottom into plate, predrill and Gerry-rig a clamp and block to hold down while you screw- use nice looking screws and and/or covers for them. Do not use drywall screws anywhere on a cabinet installation.
Second method- - pin from bottom again with clamp thingie made to hold plate down. not as good but cleaner look YMMV

Not we typically set the face of the plate out near the door plane- I like it 1/8-1/4" short make a small reveal, but can also be done just proud. Don't try to make it even with the door plane- a headache and once you adjust doors it will be off somewhere someday and look lousy.

Thanks for the advice on not trying to make them even. That makes sense.

Method #3: assemble cabinets into groups (which you should be doing anyway) and install strips of wood along the tops inset from the front and screwed down from the top. With cabinets in place on the wall, you can then pin the molding to the strips. You don't need the backing strips to be continuous, because any joins are covered by the molding. Pins are easily concealed.

DH did what Jakuvall described " screw from bottom into plate, predrill and Gerry-rig a clamp and block to hold down while you screw- use nice looking screws and and/or covers for them" He said he used small profile screws (though they require a Roberston bit, so may not be available in US), so they are basically invisible from inside cabinet. (Though I rarely stick my head all the way in cabinet and look up--LOL)