This theory by Sean T. Collins suggests that Daenerys will eventually have an opportunity to travel back in time to give herself advice. However, the crux of the idea is that the audience has already seen her time jump take place. Think back to second season when Jorah and Daenerys visit the city of Qarth. The pair have a chance meeting with a mysterious woman named Quaithe, a shadowbinder (like Melisandre) from Asshai best remembered for her checkerboard mask. Fans believe this woman is Daenerys from the future because she delivers a cryptic message that sets the young Targaryen on a larger quest: "To go north, you must go south. To reach the west, you must go east. To go forward you must go back, and to touch the light you must pass beneath the shadow."
For this time-travel theory to work, Daenerys would need Bran's power of the Three-Eyed Raven or some equally potent magic to accomplish this feat. And thanks to the trailer for the new season, we know she'll be meeting the Starks soon, so maybe this theory will bear some fruit. Nothing in the show's plot thus far outright debunks the idea except for the fact that Quaithe's eyes are brown while Daenerys's are blue. But of course, that could be part of the disguise that comes with the mask.