Dual quad question?

I have dual 600 cfm edelbrocks on my rig. I've heard that when using progressive linkage, the back carb should open first. Am I correct? Would there be a problem, if I opened the front carb first?
My set-up came with Edelbrock's dual quad progressive linkage. I can't for the life of me figure out how to set it up so the back carb opens first.
Pictures would be great.
Thanks for any help.