I'd agree that there is still another year of land grading and county approvals/permits before they start major construction. And given that most recent theme park lands have taken a minimum of two years build, I'd expect that a full park will require 3 years making 2023 the most likely opening.
I can't view the article right now but my understanding is that the grant money they got requires construction to finish by 2025, not that it will necessarily take that long. (And a project of this scale really shouldn't take more than 2-3 years.)