The countdown to Super Bowl LIII in Atlanta reaches a numerical milestone Monday: 300 days to go.

And on the same day, planning will intensify for the Feb. 3 game at Mercedes-Benz Stadium as a large delegation of NFL staffers, partners, contractors and vendors arrives in Atlanta for four days of meetings.

“It will be a key week for us,” said Brett Daniels, chief operating officer of Atlanta’s Super Bowl host committee. “A lot of these people have been here before to see the stadium or check on things around town, but this will be ... the first time they have all come together for these types of planning meetings.”

The meetings will be broken into smaller groups at several sites to hone in on various aspects of the Super Bowl, its ancillary events and venues, Daniels said.

“It sounds like it’s a long ways off,” he said of 300 days, “but the way the past 60 days or so have flown by since we got back from Minneapolis (site of Super Bowl LII), I’d say those 300 are going to go a lot faster than our group would like them to. Certainly, there is a lot to be done to make this the success we want.”

One of the host committee’s first big projects – the recruitment of 10,000 volunteers to help welcome the 1 million guests expected for a series of festivities over 10 days leading to the game -- is off to a fast start. The volunteer program, dubbed Team ATL, was officially launched with a March 28 ceremony, and by Friday more than 10,000 people had submitted online applications to serve as volunteers, Daniels said.

Interviews and background checks will follow, and the application process remains open at ATLSuperBowl53.com/volunteer/.

Volunteers will be stationed at the airport, hotel lobbies, Centennial Olympic Park, the Georgia World Congress Center, downtown street corners, MARTA stations and other places where Super Bowl visitors might need assistance.

The host committee recently announced it will team with On Location Experiences (OLE), the NFL’s official hospitality partner, to develop local events surrounding the Super Bowl. Those will include Super Bowl Live, a 10-day downtown festival featuring live music, food and interactive entertainment.

The committee also named OLE the national sponsorship agency for Super Bowl Live, designating it to work with sponsors on brand activations at the festival and other events around the city.

At this week’s meetings, Daniels said he expects progress to be made toward setting the sites of various ancillary events. But the lineup of locations probably won’t be finalized and announced until June, he said.