Your concept of time is the problem, not the notion of free will.
By the way, I claim no originality for my argument. People hae been arguing this for 2500 years. An omniscient entity is pretty much incompatible wih the human self-image as free actors. If I ask you to pick a card from a deck, you do it, and it turns out I've written down which card it was - and assuming it isn't a trick - wouldn't you assume I'd someohow rigged for you to choose that card?