In the most recent PTR build, Blizzard has reduced the number of weeks required to earn Mastery of the Turbulent Timeways V to only 4, down from 5 weeks.
With this change, players can miss 2 out of the 6 weeks that Turbulent Timeways will be available and still obtain their 
Spawn of Vyranoth mount.
What is Turbulent Timeways?
As a way to celebrate the end of a Season, Blizzard has been running this event called Turbulent Timeways. During this event, there’s always a Timewalking event happening.
Upon completing a timewalking dungeon, you earn a stack of 
Knowledge of Timeways, which transforms into 
Mastery of Timeways at 4 stacks.
Completing Master of the Turbulent Timeways
You gain credit for 
Master of the Turbulent Timeways V when you obtain or refresh Mastery of Timeways. You can earn credit towards the achievement only once a week. If you’re just looking to complete this achievement quickly, just complete four dungeons to obtain Mastery of Timeways in an alt and log off for the week. This way, you’ll only need to complete one dungeon in the following weeks to earn credit towards the achievement.
Missing Out on the Turbulent Timeways Event
If you happen to miss out on this next Master of the Turbulent Timeways achievement, or any other for that matter, fret not! When a new Master achievement comes out, Blizzard adds the reward from the previous one to the Timewalking vendors. This means that completing the achievement is just a way to obtain the mounts earlier and more cheaply.
