Blizzard released the patch 5.4 raid testing schedule for next Monday, July 8th. Hitting the PTR that day you'll be able to get a first look at the Sha of Pride and the Iron Juggernaut.
So far the testing has gone mostly smooth. There hasn't been a terrible amount of show stoppers, at least compared to other tiers. Remember that when you're on the PTR looking at these bosses, Blizzard will often make substantial changes to the mechanics and the entire lay of the fight between the first test and what ends up on live. This is common for the testing process, and is necessary to get a refined product.
Head on over and check it out! It's not uncommon to find a group just by hanging out in the chat channel, so even if you're by yourself, you'll be in luck.