Since Wanda's powers are probability based, it is likely that when she saw herself as the Scarlet Witch in her Mind Stone induced vision it was what set her on her path toward that reality. Ever since then she has been inadvertantly altering probability towards that destiny.Between it's part in awakening Wanda's powers and becoming the basis for bringing Vision to life, the centricity of the mind stone to Wanda's arc is really something.
There's something weird about it to me though, a little bit of snake eating it's own tail going on.
As you say it is the snake eating its own tail. It is almost a predestination paradox but I dont think we'll be getting into time travel in WandaVision, there's enough going on without the complexities of time travel to add to the mix.