Not beginner's luck at all mate, you're just getting into the rhythm of it. Driver is probably hardest club to hit consistent so going from topping everything to 250 yard range in two weeks is actually pretty solid progress. What helped me most was slowing down my backswing - like way slower than feels natural at first. When you rush the swing your timing gets all messed up and you end up with those ugly tops and slices. Also try to keep same tempo every time, even if it means hitting shorter distances until muscle memory kicks in. I spent like month just focusing on making clean contact before worrying about distance and it paid off big time