May nuc has exploded into a full double deep — when do I add the first honey super?

Ontario, second year but first time raising a colony from a nuc instead of inheriting a going concern. Picked up a 5-frame nuc mid-May, it hit a full deep by mid-June, I added the second deep, and today's inspection shows 8 of 10 frames in that top box drawn and loaded — wall-to-wall bees, brood on 12+ frames across both boxes, nectar shining everywhere. My gut says super NOW but my beginner brain has questions: do I wait until all 10 top-box frames are drawn (the '80% rule' says no?), does the super go on with or without a queen excluder given it's all foundation, and is there even enough season left in Ontario for them to fill it — goldenrod is still ahead, right? Don't want to repeat my mistake from last year of adding space too late and cramping them.