Here's what I do: I am constantly reviewing my LR catalog (160K+ images) for potentially saleable images and when I find/edit some I move them to the Adobe Stock Publish Service. Then every few weeks or so I "Publish" those to Adobe Stock. They sit there in my "Uploaded Files/New" section. Every day or so I pick ~6 to add keywords and titles, then publish those. In 24-48 hours, they've been reviewed and accepted or rejected. If there are any rejects, I note that as a keyword in my LR catalog (I use the keyword ASR for Adobe Stock Reject) so that I don't accidentally resubmit the same image. I look carefully at the rejected image again and decide whether it can be re-edited and re-submitted. If so, I move it to PS, where it gets a new image name and then save it back to LR. In this slow and steady manner, I'm releasing a steady trickle of images, learning what will pass the quality hurdle, and gradually building my portfolio without spending an extraordinary amount of time. Hope this helps.