What we perceive as time is the light and shadow of perception passing through the 8th dimension. All of reality is an infinite quantum fractal pattern, stretching through every possibility. What you describe as free will to choose which timeline you are on I would describe as shifting your perception into a different section of that quantum fractal.

More food for thought: The yin yang is a two dimensional representation of a four dimensional infinity symbol as viewed from within. Do you choose to go toward the light?