With the car cold...fill ET to between min and max. Close ET cap. Don't touch bleeder screw.
Key to pos 2...heater on highest temp, fan on low, 3 red dots on the dial between vents
Then start the car, rev to 3-4K rpms for 20 secs. and turn the car off.
Then open ET...add coolant if needed.
Repeat if needed. Do not overfill...stay below the max level on the dipstick.
This way you push air out, don't heat up the car, and the coolant level will reflect a true level...not the level it takes when it's hot.
You don't need to drain at this point. We're assuming you have an air bubble somewhere in the system that's preventing the flow to the heater core...the revs to 3-4K should take care of that.