So far Switzerland and Spain has the Android 11 update on their SM-N976B 5G devices. I'll use Switzerland as an estimation.
Last year Switzerland got Android 10 update on 23/12/2019 and UK got it on 06/01/2020, so UK gets the update about 15 days later.
Switzerland got the One UI 3 Android 11 beta on 29/12/2020, if we add the same 15 day delay as last year that would be 12/01/2021.
So even though us Note10+ 5G users didn't get access to the One UI 3 beta programme despite the community manager saying so, hopefully we get the stable official update around the 12th-15th of January 2021 if everything goes to plan!
Edit: Baltic and Romania got the update on the 6th Jan, total of 4 countries have it now.