NEW YORK -- Kindergarten marks a major milestone for kids and even their parents, and the age of 5 is the standard time to get your child registered for school, depending on their date of birth.
But now, many parents are opting to wait an extra year to enroll their kids.
It means their kids will be among the oldest in class, and many see it as the gift of time. The practice is called "academic red-shirting."
But for some parents, time is money.
"If I were to red-shirt my child, then I've got another year of pre-school costs and daycare costs," parent Jessica Hoff Berzac said.
Berzac and her husband have three sons. Walter starts kindergarten this fall when he turns 5, and he'll probably be the youngest and smallest one in class.
"He's resilient," she said. "He'll do fine."
To register in many districts, kids must turn 5 on or before September 1, but clinical psychologist Dr. Susan Napolitano says more and more parents are holding kids back, especially if they feel their child isn't ready emotionally.
"So a kid who's younger and maybe not super advanced socially might have an advantage if you can make them an older kid in the school," Dr. Napolitano said. "So they don't become a social outcast."
Berzac is not a fan.
"I immediately associated it with the concept of helicopter parents and these parents that want to kind of manufacture their children's lives," she said.
The National Center of Education Statistics says in 2010, 9 percent of the kids started kindergarten when they were already 6 years old.
"We haven't seen a large trend in our district with that, but I heard of that in some of our neighboring districts," said Wendy Hernandez, of Central Unified.
Hernandez says another option, transitional kindergarten, allows younger kids with summer birthdays a chance to essentially take two years of kindergarten to improve academically.
"You have to think beyond just right now, but think long-term" she said. "What would be best for them?"
In any kindergarten class, you'll have younger and older students. But a new study by Harvard Medical School certainly gives parents something to think about.
Tim Layton is a professor of Health Care Policy at Harvard Medical. From a sample of over 400,000 kindergarten students, he discovered a trend.
"Children born in August are much more likely, about 30 percent more likely, to be diagnosed with and treated for ADHD than children born in September," he said.
The learning cycle is well underway for 5-year-old Carsten. His parents placed him in transitional kindergarten in September, but Carsten wasn't quite ready and kept acting up in class.
"We put him back in pre-school, back into his old pre-school, and we've seen a 180-degree turn in his behavior from what it was in the TK classroom," mom Alisha Gallon said.
Carsten is a bright kid who has been diagnosed with ADHD.
"But there are children that grow out of it, and I hope he's going to be one of them," she said
Dr. Napolitano says six months can make a big difference in kids at this age.
"Expecting a child of a young age, especially a boy, to sit still for long periods of time may be more than they can handle," she said.
Many parents wouldn't think of delaying the start of kindergarten, but others though, seek not just a social and academic edge for their kids but success in sports as well.
"You want to give your kid every advantage you can," Dr. Napolitano said.