Increasing UX maturity of an organization

I was asked by my boss to implement the UX practice in our organization and our UX maturity is like 2/10. It is a 70 years old financial organization with lot of departments and many of them got their own UX departments and designers. It will be a challenge to bring everyone on board under one UX hub (there may also be resistance from other departments). Q: Once I assess the UX maturity in our organization, what should I do next in order to make sure that I am moving the UX maturity from lets say 2 to 3? And what process shall I follow and what the timeline may look like?