You're tapping in to the “now” in a very interesting way. This forum is not the place to give you extensive esoteric answers to the puzzles outside of your perception. Even the answers I give are often seen as too long.
A metaphor: See your reality as a life that has many tracks or potentials that you call “the future.” Everything you've done and all those potentials together make up the “whole” of the now experience. In your mind, place this “now experience” in a very large balloon-shaped space, where they're pasted to the inside of the balloon's interior. Now, place yourself in the middle of this balloon and look around. You're now standing in a place where everything you did is there, along with the potentials of everything you might do. There's no predestination, but plenty of avenues of potential. But since you're looking at everything (esoterically), you're “feeling” it, too, and you actually have some kind of interdimensional foreknowledge of what might happen depending on the road you take.
Now, return to 4D. Even though you're sitting there reading these words in normal reality, there's still part of you that's always in that balloon, but you're not aware of it. So when some of these potentials finally happen, there's part of you that says, “I've been there and done that! Wow! Déjà vu!” All that has really happened is that you're just recognizing the potentials you built for yourself, and felt early, which are now manifested into your linear reality.