So I buy phone without contract at Johan Lewis shop and I buy pay as you go from three and I still don't' have update
So this few guys from three maybe use xda step by step to install firmware ?
If you use it correctly it will not trip knox
TWRP? Yes it will trip the Knox. There is no correct or incorrect way with custom recovery. Custom Recovery will trip the Knox. Some people use custom kernel to fake the Knox counter and people think that works. It only fools some apps but the real hardware Knox viewable in the download mode will be tripped. That's what Samsung use to check on the Knox status.
So thats why better wait for OTA
To many things to lose
He is talking about TWRP. You DO NOT need TWRP and should not use TWRP. Just follow the instructions here and not on XDA.
The update is done with Samsung Stock Recovery and there aren't too many things to do and it will NOT trip your Knox and it will not erase your data. If you don't know what stock recovery is and how to get to it, please wait for the OTA. I assumed that all beta testers should know how to get and use the recovery mode since you would have had to use it multiple times to clear the cache which seemed to be the only solution Samsung offered during the beta :-)