Non-emergency patches are applied to the live servers on Tuesdays.
As Nevalistis mentioned shortly before Season 19…
…they want to patch at least a week ahead of a new season starting. The only Tuesday that satisfies that condition is Tuesday, March 3rd. As the patching is done in the Pacific time-zone, this usually means that it’s done at the equivalent of 01:00 or 02:00 CET Wednesday morning.
So, you’re most likely looking at being able to play 2.6.8 on EU live in the early hours of Wednesday, March 4th.