We have no access to the RFE, and your question is a bit muddy. If they are asking for start and end dates for each period of employment, then you would provide those dates for each employer (if there's more than one). If there's one employer involved, you have told us that you started in August, 2015. Beyond that, consider asking your employer(s) to give you a letter stating your start dates and (for any past employer) end dates.

