From “terrible twos” to quinceaneras on the 15th birthday, lots of childhood goes by the numbers. But kindergarten is one milestone parents should base on their child’s readiness, not their age. While many kids are ready for kindergarten when they’re five-years-old, quite a few aren’t.

It may seem like no big deal to send your kid a few months early. But that strategy can backfire. “Success or failure at this stage can affect a child’s well-being, self-esteem, and motivation,” noted the Mayo Clinic. “As a result, it’s important to make sure that when your child begins school he or she is developmentally ready to learn and participate in classroom activities.” To make the call based on the kid, not the calendar, follow these tips:

Know the stakes

If a child enters formal school too early, she may not have the ability to sit still and focus, which can negatively impact school success through age 11 or later, according to a 2016 Stanford study. “We found that delaying kindergarten for one year reduced inattention and hyperactivity by 73% for an average child at age 11,” Stanford professor and study co-author Thomas Dee said in a release.

This may make you think later is better, but that’s not true for every child. Would you really want to be that parent who holds their child back intentionally so they’ll be the biggest, smartest, and have a better chance at succeeding in sports? That can result in your kid being bored or developing behavior problems during adolescence. According to the Mayo Clinic, “research suggests that children who are old enough for kindergarten but postpone enrollment for one year don’t perform any better than children who enter at the usual age – particularly if the child remains in an environment where readiness wasn’t being fostered.”

Determine your district’s cutoff

The first limit on the kindergarten decision will come from your school district. It ordinarily has a cut-off tied to a certain birthday. Most schools allow parents to delay entrance by a year on request, but few will let a kid in early. If you find your public school isn’t willing to work with your decisions about kindergarten readiness, some parents explore Montessori schools or home-schooling for a year or two to avoid the age-readiness question altogether.

Conduct an interview

This is a great time to start being a partner with the people responsible for educating your child. Instead of just leaving the choice to the state cut-off, spend some time analyzing your child’s readiness, ideally together with your child’s other parent or primary caregivers. The answers to these questions will help you know if your child is ready, licensed clinical psychologist, Dr. Elizabeth Matheis, told Parents:

Does your child get along well with preschool classmates?
Can the child initiate a conversation and maintain it for a short while?
Is your child able to sit still for at least a few minutes?
Can he ask for help? Write his name? Speak the alphabet?
Does the child know the sounds letters make?
Does his conversation make sense, at least most of the time?

What your answers should reveal is whether your child has one critical kindergarten readiness skill: “He should be able to express his feelings in words,” Matheis explained, “as opposed to yelling, grabbing, crying, or throwing himself on the ground.”

Focus on readiness, not skills

While it’s cool if your kid can already recognize flashcards or count to 100, you don’t want to focus on specific skills, according to the Mayo Clinic. Instead, try to predict whether your child is ready to learn.

Involve those who know your kid well

Rather than making a big, once-and-for-all pronouncement independently, it’s a good idea to involve some other opinions. Don’t ask anyone to draw conclusions for you, but do ask other caregivers and your preschool teachers for input. Instead of asking, “Is Bailey ready for kindergarten?” ask more general questions. “Is Simpson getting along well with the other kids in the church nursery?” or “Have you noticed if Bill is able to sit still for more than a few seconds?” are more likely to give you the information you need without making you feel defensive.

If you start getting input at least a few months before kindergarten registration in your area, that also gives you a chance to compensate for any lacks. If your babysitter says your kid doesn’t know how to start a conversation, for example, you’ll still have a chance to promote your child’s social skills with extra play dates or other group activities. Throughout, make it a point to rely on your own gut feelings, too, especially if you’re thinking your kid isn’t ready yet. If you’ve done all the conversing and soul-searching and still don’t have a firm idea of your child’s readiness, consider consulting your pediatrician before making the decision.

Consider the long-term

It may be difficult to take this decision too seriously when your kid is still playing in a wading pool and requesting juice boxes, but some of the results of postponing kindergarten for a year are long-term. There’s potential boredom, sure, but your kids may also be the one getting their driver’s license a year earlier than her classmates. If she entered kindergarten at age six, she may also be hanging out with older kids who then leave for college when she’s still got a senior year ahead of her. One way to balance this aspect of the decision is to call the office at your school district. See if someone there is willing to talk you through the decision to enroll or wait, and give you information about what happens if you change your mind and want your kid to skip to the age-appropriate level in a few years.