Officially, McDonald's will not begin its eagerly anticipated plan to serve breakfast all day until Tuesday.
But some early-bird markets are already filling these orders throughout the day in pockets of the country, including Ohio's Miami Valley and Northwest Florida, according to Twitter posts from McDonald's markets in those areas.
In an email, McDonald's spokeswoman Lisa McComb wrote, "Customers are excited about the national launch of All Day Breakfast next week. Restaurants are free to offer as soon as they are ready."
Markets in Nashville, San Diego and the Mississippi Delta that have been testing the idea also serve it throughout the day.
Since announcing the nationwide initiative, the chain has been running a full-court advertising press to build excitement and get so-called Breakfastarians who eat breakfast dishes regardless of the time of day in the door once it launches. The push has especially targeted a younger, tech-savvy crowd through extensive use of GIF images.
Extending breakfast is one of the largest initiatives for the company in recent memory and could add complexity to operations, which McDonald's has been trying to simplify through menu cuts to make the ordering process speedier.
McDonald's is counting on longer breakfast hours to help regain momentum at its struggling U.S. unit, where performance has lagged many of its peers amid increased competition from fast casual brands such as Chipotle Mexican Grill and fellow fast-food players like Sonic.