I set them up by eye first.
Generally I find it`s always a bit out after starting the bike up.
I find it`s much easier to have the bike running.
Once it`s up to temperature, I find it`s very easy to balance the carbs.
After each tweak of the adjuster screw, let the engine settle. Then give it a couple of rev-ups & let the throttle go to settle the linkage.