when to add foundation supper on drawn comb supper

[jsmob]

Hi folkes.
 I will be starting two packages of bees this year. I have two supers of drawn comb that I will be putting them into. I know that if you start them on foundation that you wait til about 7 frames are drawn before you add another super. My question is, can I just set a super of plastic foundation on them right then or do I wait? When do I put the next super on?

[Understudy]

You wait until you are 80% full. The frames need to be full of brood honey and pollen.

Sincerely,
Brendhan

[jsmob]

Thank you for the info.