Spells on a stick always need to be more expensive. Sometimes a lot more. It wouldn't work if it was cheaper than Eternity, and having 6 creatures or just a couple (2-3) that can do Rewind would be way too strong. Flying Eternities are balanced because you need a spell to make them flying.
Deja Vu could work if the cost grew exponentially with creature power, but that seems needlessly complicated. Precog would make Time Nymph even less used than it already is. How about the ability to Delay a targeted creature for 1 turn and 1
?
Of course, there's no real need for granting a skill. If the Element becomes Time, I would suggest it means the cost to play it also becomes Time. I suspect that's what you intended, but I think it needs to be stated on the card.