If I were you I would get all that done now.
Try to have your machine clean and barebones, and locked up tight before the deadline. After you think you have most of the vital updates from the update center, keep visiting it and running custom update search. Download a free program to update all your drivers, Avast or glary utilities will check for updates, for your software.
If you do a new install, it will take a while to get everything up to the newest current level, the updates unlock and lead to new updates, it can take several days to be completely good to go.
...have your machine clean and barebones...
--but what about authenticating with MS?
I'm trying to install a old copy of XP that I got to make a virtual machine with Oracle Virtualbox and am wondering how I'll be getting around the two-week pre-authenticate limit.