Back in the day, when we were were only concerned with the core Avengers' shenanigans, it was fairly simple to work out where each new movie fell on the Marvel timeline. As the franchise has expanded, though, and introduced things like incursions, variants, and alternate realities, things have gotten a lot more difficult.
In the case of The Fantastic Four: First Steps, then, it's basically a question that only Reed 'Smartest Man Alive' Richards himself could answer. You see, for the first time since the long-running series kicked off in 2008, the film plays out completely separately to the events of Captain America: Brave New World, Thunderbolts*, and more – and doesn't introduce Marvel's First Family to Earth-616 like Deadpool and Wolverine did with its titular heroes.
