The Threads of Fate is unlocked after completing the story and reaching level 60 on at least one character in Shadowlands.
Once you reach level 60 and complete the upgrade campaign on your first character, you will unlock the Threads of Fate feature for your alts. This system allows you to choose your alliance immediately after you register, and it will mark the campaign as "completed" for that character. However, there are a few wrinkles that you should be aware of before choosing Threads of Fate.
All characters will need to complete the introductory quest chain for Shadowlands in the Maw. This means heading to Icecrown, creating the portal to the Shadowlands, and then escaping the Maw. This can be completed in about 30 minutes to an hour, but it is a bit difficult to repeat the entire sequence over and over again on multiple alts.
Once you've escaped the hangover and arrived in Oribos, time will freeze and you'll be greeted by Fatescribe Roh-Tahl. This is your first opportunity to select Threads of Fate, but you are free to replay the scenario and participate in Threads later by returning to Oribos and speaking with Fatescribe. That said, choosing Threads of Fate is a permanent choice in Shadowlands. Whether you choose it after escaping the hangover or later, you're locked in. For this reason, you will receive a prompt asking you to type in the word "FATE" to confirm your selection, and attached you will find a warning that your choice is final once you click Accept.
The Threads of Fate system isn't a bad way to level alts, but as of post it might need a little tuning. Choosing your Covenant early means you'll have access to your Covenant abilities out of the gate, and you can farm Anima as you level up. You'll still need to reach level 60 before unlocking Fame Quests, Soul Bonds, and other endgame features, but it's a start. You will have access to the world quests, all the main side quests will be marked on your map and you will be able to visit any area of your choice. Dungeons are still level limited, but these and PvP can be used to level effectively. The tuning issue is associated with bonus objectives: currently they take too long to complete for the rewarded experience.
If you are looking to level as fast as possible, history is still the most effective route. Keep in mind that if you reach level 60 while playing the story, you will be excluded from the Sons of Fate. This means the most optimal way to level up is to stick with the story until you're level 59 and near 60. Before you jump in that last time, head over to Oribos and turn on the Threads of Fate, then complete your upgrade. You'll skip any story quests you have left over and go straight to the end of the game. That said, repeating the story ad nauseum gets old pretty quickly, so if you don't mind the slower leveling pace, peak the levels. Threads of Fate.
