Hi @Anonymous User
I don't think Sky / NowTV have an official date yet for Season 6.
Where looking at previous seasons this TV series starts later over here (some time in the Winter maybe somewhere around December time in the UK) compared to the States where i believe Season 6 has already started.
Perhaps consider signing up for the free Sky Never Miss service where you will get an email notification when Season 6 or any other TV shows that you are interested in that is due shortly on the Sky service which is normally mirrored on NowTV with the same dates.
Link to Sky Never Miss Service.
https://epgservices.sky.com/nevermiss/
