@evankitson I'm still getting the hang of Ello, too! The message/reply process feels a little clunky, for sure. And no worries - I love to talk shop.
Re: copper. I definitely prefer it unprimed.
I've been getting 18g and sanding with fine grit > a few wipe-downs with isopropyl alcohol > rubbing the surface with garlic juice. I then do a couch of Oleogel. You could skip the Oleogel if you don't mind drag. You'll want to use lead white pretty much throughout your first pass as it bonds with the copper, but you probably know this already since it sounds like you've been priming them.
I'm told the garlic causes some etching and helps the paint to bond with the surface. I'm also told it's controversial. I like it and have had no problems so far. This method gets that lovely satin/developed surface pretty quickly, and sanding it (I like to sand most paintings at least once) is really enjoyable. And copper dries fast. Hope this helps & hope you have a blast! It's one of my favorite supports so far, though I haven't tried dibond yet.