... started immediately on Monday in his first major-league at-bat when he ripped a three-run, first-inning homer over the right-field fence to send Atlanta's Turner Field into a frenzy.
Did it start when he received the ceremonial first-pitch before Monday's game from Hall of Famer Hank Aaron?
Did it start this spring, when he drilled a distant Coke truck and smashed the sunroof of assistant general manager Bruce Manno's car during one round of batting practice?
Don't look now, but it may be time to start scripting The Natural II.
"I'm not trying to do anything other than get ready for the season," Heyward, 20, told me this spring as the buzz around him grew. "I've been trying to win a job ever since I've been in the organization."
That would be all of, oh, one full professional season.
Heyward's was the most anticipated rookie debut of 2010 -- at least, until Washington recalls pitcher Stephen Strasburg -- and all he did was jack expectations even higher, if that's even possible. The Braves measured the homer at a monstrous 446 feet.
After the Aaron moment, and after outfielder Marlon Byrd had staked the Cubs to an early 3-0 lead, the kid stepped to the plate with the score 3-3 amid chants of "Let's Go, Hey-ward!" His parents, Dartmouth College graduates, were in the crowd -- on television, the Braves broadcasters said that Heyward told them he was leaving tickets for about 50 people today.
The pitch Heyward crushed wasn't a bad pitch. Cubs starter Carlos Zambrano left it over the plate, but it was down toward Heyward's knees. It wasn't like Zambrano left it up. Didn't matter, the 20-year-old phenom crushed it. Paul Sullivan, long-time Cubs beat writer for the Chicago Tribune, tweeted that Turner Field was louder than he's ever heard it as Heyward's ball went out.
Had Heyward not signed with the Braves after they made him their first-round pick (14th overall) in the 2007 draft, he would be a junior at UCLA today.
Instead, he's climbing the charts with a bullet.
Scouts this spring already were comparing him to Dave Parker and Darryl Strawberry. One former manager who knows both Parker and Strawberry told me that Heyward is far more mature at his age than Parker or Strawberry were at 20 -- another indication of impending greatness for Heyward.
"If you put in the hard work, it's reflected in the results on the field, in how everybody sees you and in you as a person," Heyward, who went 2 for 5 with four RBIs in his debut, a 16-5 Atlanta win, told me this spring. "It pays off."
One major-league at-bat in, it already is.