I looked at a bunch of recipes and then actually read the thread to figure out your question was already answered.
I couldnt find any turkey ones.. lots of vegetables and chicken ones though. They asked you to brown the meat a bit first, then throw it in the pot with some herbs and the vegetables and then to turn it on for a period of time. So yeah, you put them all in at the same time.
Although if you were going to cook carrots by themselves in the pressure cooker, you would cook them for a shorter amount of time than you would cook the turkey solo. My pressure cooker cooks most vegetables in 2-5 minutes (this is AFTER it gets up to temperature/pressure so its really like 10)