Any craft items could be listed from July, as that's when leading craft companies start their major promotions (one leader calls their sales push "Christmas in July"). For instance, your rolls of ribbon (for decorating cards, such as ribbon-threading, or decorating card/gift presentation boxes - boxes that a crafter's probably made themselves), and yes maybe even the napkins as some crafters like to apply certain techniques to them to turn them into card toppers (see YouTube tutorials for how to do it).
It's like an arms race, with the major craft companies trying to get ahead of their competition, so that you start seeing items in shops, including eBay shops, in late June!
I don't sell on eBay, I only buy, but I believe that when you list you can assign your items to categories. The crafting section is a large category.
Some crafters buy a lot of stuff in late December and in January, ready for the next Christmas; some even start making Christmas cards (and decorations etc) in January, though usually people will start in August or Sept.
