I mean, is it too soon if people are still going to buy it? More seriously, I think one whole console generation is a good standard for remasters. Just so long as you can point to something that looks or plays better than the original did. For a remake, I think you need more time and the game your making needs to feel like it couldn't have been made on the original hardware. Either way three years feels way too soon, especially for what is essentially a next-gen port or a definitive edition.