Well i just overcarbed my 6ltr so dont do what i did and follow instructions assumed for 19 ltrs hahahhaha. I adjusted it now over last 24 hrs and ita been pretty good.
If you know the temperature of your beer during carbonating and the volume of CO2 that you want, you should never go wrong. There is stacks of tutorials on carbonating.
All depends on how patient/impatient you want to be.