DEL MAR, Calif. – If the waiting is the hardest part, as the late Tom Petty opined, then training for this year’s Kentucky Derby has brought an unprecedented challenge. In mid-March, Authentic and Honor A. P. were coming off a one-two finish in the March 7 San Felipe, with both headed toward a Santa Anita Derby that was scheduled for April 4, while Tiz the Law was readying for the Florida Derby at the end of that month. All three had been trained in the hope of peaking on May 2, the original date of the Derby. Yet on March 17, it was announced the Derby would be postponed four months, until Sept. 5. In the months since, such highly regarded Derby prospects as Charlatan, Maxfield, and Nadal exited the scene, while late developers like Art Collector and Caracaro came on. Through it all, though, Authentic, Honor A. P., and Tiz the Law have remained top contenders for the Derby, a testament to the skill of their trainers and the ability and consistency of the horses. “You just had to take a little more time and hope everything worked out,” John Shirreffs, who trains Honor A. P., said at Del Mar this past week. Shirreffs as well as Bob Baffert, who trains Authentic, and Barclay Tagg, who trains Tiz the Law, are all Derby-winning trainers. The three navigated the uncharted waters in different ways. Shirreffs, who won the Derby in 2005 with Giacomo, said he worked with Honor A. P. on “trying to teach him poise” because “he’s going to have to deal with adversities, and you don’t want him to fall apart just because you have to stop.” “It’s not always going to go his way,” Shirreffs said. :: KENTUCKY DERBY 2020: Derby Watch, point standings, prep schedule, news, and more Baffert, a five-time winner of the Derby, eased off the gas pedal with Authentic, not wanting him to get too revved up too soon for a Santa Anita Derby that was pushed back two months, to June 6, owing to Santa Anita being shut down for racing, at first with no firm date for resumption. “I stopped on him, completely shut him down,” Baffert said. Tagg, who won the Derby with Funny Cide in 2003, said he changed little with Tiz the Law, believing the colt wanted more thrown at him. Following the Florida Derby on March 28, Tiz the Law remained on a schedule that had him breeze once a week leading up to his next start, the Belmont Stakes on June 20, and he has stayed on a similar schedule through the Runhappy Travers and now on to the Derby. “He thrives on workouts,” Tagg said in a telephone interview from Saratoga on Tuesday afternoon. “He seems to thrive on everything we do. He gets a good gallop, a mile and a half to a mile and three-quarters, every day, works Saturday or Sunday depending on the weather. “He’s an easy horse to train that way, a strong horse. He seems to thrive on what we do. I’m always wondering if I’ve done enough or too much, but he runs the same race every time.” Honor A. P., following the postponement of the Santa Anita Derby, stayed on a fairly regular work schedule of half-mile and five-furlong drills, nothing demanding. But each work and each training session in between had purpose. “Some works weren’t as important as others, but a young 3-year-old needs quite a bit of exercise,” Shirreffs said. “Every day when we’d take him to the track we’d try to teach him different things, like to relax and use his stride in a more efficient manner.” Until a firm date was known for the Santa Anita Derby, “On the days he didn’t work we’d alternate gallops and jogs, gallops and jogs, knowing that there was going to be a lot of time between races,” Shirreffs said. Honor A. P. responded. He won the Santa Anita Derby, beating Authentic, reversing the result of the San Felipe. Authentic, by contrast, did not work between March 29 and April 27. He then had six works leading up to the Santa Anita Derby. “He came up short, and he broke badly,” Baffert said of that race, his lone loss. Since then, Authentic has stayed on a regular schedule of works, and has raced once, winning the Haskell. Since returning here following the Haskell, he has worked five times, the last three at six furlongs, six furlongs, and, on Tuesday, a one-mile drill in 1:38.60, mirroring the kind of workload Baffert has demanded of his Derby prospects when the race is in May. “You’ve just got to deal with what you’ve got,” he said.