It took them two days to get back to me after I signed my agreement, but that was last year. The process has changed slightly since then and as KeithCurtis mentioned, we just got a new Marketplace manager on board. Once they get you set up, it's pretty simple to upload everything you need and submit for approval. They do have to approve the set, but that's mostly to ensure it's in the right format,tagged for searches, and fits their basic community standards. I would highly recommend you start tagging your assets now by changing file names to "Item Name[tag1,tag2,tag3]" format so you don't have to go through and tag every item when you upload it later.