PIP review / claim due to end

Hi, my PIP is due to end on the 23rd November, I have had an extension to return my review as I didn't receive the forms and my review is due on the 10th December. As my PIP is due to end on the 23rd, is it best that I make sure my review is back by them as they'll likely extend my award due to extensions taking so long currently? Does anyone have any idea what the review timescale is at the moment? Last I heard it was 12 months? Any help is much appreciated :)