Either way, as a former customer support representative, I would suggest you to delete the game entirely and redownload the game to avoid issues.
Not that I don't trust Larian's patcher, but if you don't have download limitation, there isn't much reason to simply patch.
My question would be, will we be able to predownload the game like 24h hours before ?
I'd like that because I suspect the download would take a bit.
TBH I was thinking on doing that day or two before, I mean I am not playing DOS2 now anyway (just counting seconds until it is released) but still, when they released DOE EE they said that we will get "new game" in steam library instead just paching on old file.
(unless I forget to uninstall it
