If God created the universe suddenly, he created it in a state that is indistinguishable from true age. If he did create it that way there must be a reason, otherwise God is a liar. Whatever that reason may be, a universe that is exactly like one that is old should be treated as if it were old. Because God did not create the world in seven days does not mean that he couldn't. What did, or did not, happen is not an indication of what could, or could not, have happened.
All evidence suggests that evolution is the way things happened.
Regardless of what could have happened, the evidence would still point to evolution. Evolution and Proof Q9. Nobody can really prove anything anyway. Except, of course, in mathematics. However, science does not require absolute proof, otherwise science textbooks would be empty.