The historic $1.5 billion expansion of the Javits Center will be “substantially complete” by March 2021, Gov. Andrew Cuomo said Saturday.

“We’re on time and on budget, which are the two favorite expressions that I love to hear,” Cuomo said from the roof of the massive project, which will add 1.2 million square feet of event-related space on Manhattan’s West Side.

The expansion’s steel and concrete superstructure is finished, and installation of the final phase of non-structural steel is underway.

The new Javits will be roughly 3 million square feet, feature a 53,000-square-foot ballroom and create 6,000 jobs.

Cuomo called the convention center “another milestone in our redevelopment of New York.”