I will describe how I do it when I charging thru low side.
If I know total amount, I charge by weight reading the amount drawn on scale and throttling on manifold valve.
I usually keep rate of charging by 2-5% (higher at beginning and lower at the end of charging process) of total charge in one minute, while watching that sight glass on my Refco 4 valve manifolds is not full of liquid (I keep sight glass with lots of bubbles). After 1/2 to 1 minute, I stop feeding refrigerant and wait for another minute or two that accumulated refrigerant (if any) evaporates. Then I start feed refrigerant again.
If I don't know total amount, I charge slowly, keeping sight glass on manifolds without liquid and interrupting frequently to check pressures. When they are near to be good, I look in scale and proceed with charging about 1-2% of total amount charged so far.
Now, I measuring subcooling, after some time system stabilize, and judging if it is more needed.
That is my way, which I adopted from my experience and after reading a lot of articles about proper charging methods. It works relatively fast and it is accurate and don't make any damage to system.