It can be quite difficult to begin the new WoW expansion. There's a long, even huge adventure ahead of you, 10 levels to reach (up to 120 levels) and hundreds of new quests. The question about how to get to Silithus is actually how to start the expansion of Battle for Azeroth. We present few ways to get to Silithus from both sides - The Horde and The Alliance. You will learn how to get the Hearth of Azeroth necklace and what conditions you have to meet in order to unlock your quest.
When you have completed your third zone, you should be nearly max level, but you still have work to do! Head back to your faction hub and complete the last foothold quest to unlock your fourth mission table champion. After, you will want to do your newly available invasion missions for your faction. This quest chain is one that will be time gated by reputation levels earned with the 7th Legion for the Alliance and iThe Honorbound for the Horde. Complete as many quests as you can and then finish up your leveling with side quests you may have left in previous zones as necessary.
For reference, my previous best time abusing Method-0 in 7.3.5 was 32.4 hours(as show in the old thread). A difference of just over 8 hours; which isn't all that bad, all things considered. And I believe I made several errors along the way, which could be cleaned up in future runs. I believe that that gap could be significantly closed by using a monk's bonus, but I hate playing monk...so...yeah. YMMV