Officially each time you add a document and hit submit you go back to the end of queue and that date is your new submission date.
But we have some anecdotal reports here of about three people who have added documents BEFORE being reviewed and maintaining their review submission date.
If you have been requested to provide a W2, and have not done so and have not provided an explanation of why you don't have one I suspect they will RFE you again. I would recommend you add a signed statement explaining why you don't have a W2 for the requested tax year.
ROI-AL reacted to Saqib-s in Adding additional documents after submitting