Well, He's God and I'm not. I don't pretend to understand His mind or what the concept of 16 billion years means to Him. He made time. Do you see how meaningless it is to judge the maker of time by our ideas about how He should have accomplished things or how we could have done a better or more efficient job of creation. The Soviet Union was a very small scale attempt at "creation."
Weak analogy, due to our comparatively limited understanding, but here goes:
Imagine a ruler laying on a table in front of you. You can move to the left, right, above, below it, pick it up, move it, turn it around, and most of all, see the whole thing at once. You definitely are not constrained to living on that ruler. You could even smash it and get a different ruler if you wanted, or have several rulers on your desk.
That ruler is represents all dimensions of the universe, including time, forever, as viewed by God.