I was able today at 6am EST to copy two of my characters into the USA PTR 2.4 hopefully you are lucky to get in. Go, Go, GO!!! I had logged in a day ago with a level 1. Trust me, it is hard to swim at that level with fatigue killing you half the way. Need to be a priest level 4 to make it through.
At level 70, if you are Horde simply go to the Silvermoon flightpath to fly to Sunwell Isle.
Alliance players may go to Ironforge or to Zul’Aman to fly to the Sunwell. I heard there is a teleport in Shattrath City, but I haven’t confirmed that. The flightmaster in the Sunwell is at the north of the isle, just to the west of the boat port. The Shattered Sun Quartermaster is south of the boat by the High Elven tents. The T7 gear and transmuter of the Sin’dorei Relics NPCs are on the boat. Safe journey!
UPDATE: Europe PTR is officially up according to Vaneras:
Vaneras: The 2.4 test realms (PTRs) are now live. You will have the opportunity to discover Sunwell Isle and the latest new content. 2.4 patch notes can be viewed here.