Hello,
As always, it depends on how is your business!!
Anyway, if I have to choose I think you should consider the customer requested date that you have in the sales order.
Suppose that your customer requested 100 CS in Nov and 100 CS in Dec. Now, suppose that you had capacity constrains and you have not been able to deliver a single CS in Nov, so you only delivered 200 CS in Dec. What do you want to consider to plan the future? 200 CS in Dec or 100 CS for Nov and 100 CS for Dec.
Hope my point is clear.
Kind Regards.
Mariano