I was in this boat for literally almost a year, trying to get my listings, mailing list, social media, everything super 'ready' and on point, but I realized that there will never be a perfect moment, I had to put aside that fear and just start posting. I still have a plan, sure, but waiting to have EVERYTHING in order was simply keeping me from doing anything. As someone else said, you can't sell anything that's not listed. I had a bunch of designs I had made over the months so I'm not creating new stuff every day, but I am still putting them into the mockups/listings a little bit at a time and I think staying consistent with your activity is better than releasing a big collection and then disappearing. I think this is the difference between etsy and somewhere like shopify, if you were opening a store on shopify you gotta have a whole catalog ready to go because you're driving your own traffic, but etsy has a search function to bring in a steady stream of viewers and also an algorithm that likes to see you (and buyers) coming back.