I can go back as far as I want to make adjustments to our estimates. I can only go back to the 7th generation as we didn't start weekly estimates until that generation. I have no way of editing older sales for the Platform Total page, but there are plans to add an edit button to those figures sometime in the future. Right now we only have one main developer and there is a lot we want to get done.
Thanks @trunkswd for your answer. My question was geared towards on average how many weeks or months does it take for you to receive new data that allows you to make a revision. Is it only when you get Official nintendo reports or is it sooner than that.