Thermoquad Vent Tube

Gonna start my engine and break in the cam this Saturday!
Prepping to first start up, brand new (rebuilt Summit) Thermoquad...I was advised to fill the bowl ahead of time through the vent tube.
Stupid question, but the vent tube is the tube in the FRONT of this picture - yes?



About how much gas should I put in it? I don't want to overfill it....

Jeff