The drop is "smart loot" meaning if you're not an engineer or not maxed level engineering, you will not see it drop. Only engineers with 600 skill will see it and be able to roll.
Now, my biggest question was whether or not this loot was exclusive to a level 90 player or not. To test it, I hopped onto my level 86 engineer on the PTR and joined a level 90 friend. After reaching 600 engineering, and a few kills in the Vale (we killed a few of the new sha mobs and then a neutral crane), the schematic did indeed drop for my lowbie. She was able to learn all of the recipes without any hassle.
This is EXCELLENT news, and I hope this doesn't change come 5.4's release. Both pets are BoP, and the mat necessary to craft them is also BoP, making this pet pretty exclusive to engineers. Unfortunately for some (like myself), not all engineers are level 90 yet BUT have max skill in the profession. By making the prerequisite only 600 engineering skill, it gives more players the opportunity to craft the pets for themselves.
Players who aren't level 90 yet will need to find a max level partner to help them 1 - reach the Vale of Eternal Blossoms, and 2 - kills mobs within this zone to get the schematic to drop. It would be lovely if you could cage and then trade Pierre or Rascal Bot to anyone that helps, as a show of thanks, but oh well. Profession exclusive pet is exclusive.
As a sidenote, if you have an toon with engineering but need a bit of catch up to reach 600 skill, here's a handy guide to quickly level engineering. I'm definitely going to be following this guide so I can reach max engineering before 5.4. :D