I've heard a LOT of WandaVision Theories, but I'd like to hear if any members of this community have some. I have a couple the first one being:
In-Universe Theory: The series premiere opens with Wanda and Vision driving into Westview, with the "Just Married" sign on the back of their car. They will drive into Westview, settle into their home, where they'll find Agnes waiting for Wanda, as she walks in, Agnes gives her a hug, and asks her what she is doing in that house. Right then, Vision walks in, the first look we get at him as a human, as Wanda uses her powers to make his hat and robot-ish face go away. Agnes leaves, and Wanda says that she wants to fit in, and Vision responds that they shall.
Out-Universe Theory: All content that we see that's black and white from the trailers, will be in the first episode. We won't get a first look outside the alternate reality until at least the end of episode 1.01, but that's in Part 2!