(CNN) - It could happen at any time: Eventually, your kids may want their own social media accounts.
"If you have a teen or tween, you should expect them to come home around the beginning of the school year and say, 'Oh, I want to download so-'n'-so,' " said Caroline Knorr, a San Francisco-based parenting expert with the nonprofit organization Common Sense Media.
Yet at what age do most children launch their own social media presence?
In the United States, "our understanding is that about half of kids have some form of social media by age 12," Knorr said, referencing a Common Sense Media census report released in 2016.
The report was based on a nationally representative survey of 1,786 parents in the United States whose children are 8 to 18. The survey was conducted in July 2016.
The report found that, overall, 56% of the children had their own social media accounts, based on the parents' survey responses. Among those children, the parents reported that the average age when initially signing up for the account was 12.6 years.
Separated by age range, 80% of all teenagers (ages 13-18) in the group had their own social media account, compared with 23% of all tweens (ages 8-12), the parents' responses revealed.
Vivian Friedman, a child psychologist at the University of Alabama at Birmingham, pointed out how children ages 6 to 12 develop the ability to think in concrete ways, and then during adolescence, between 12 and 18, they acquire the ability to think more abstractly.
Since children think more concretely before adolescence, some may not be able to fully "analyze the truth or validity of abstract issues" related to social media, Friedman said.
So whenever parents allow their children to have social media, "I think that the best way to do it is to sit down together and explore the program that your kid is interested in using -- and explore some of the privacy settings that they can use," Knorr said.
"Then it's important for parents and kids to talk about what is appropriate to put up and what is not appropriate," she said. "I do think around 12 years old is when kids have that capability to follow your rules and to understand that those rules are really important and set in place to help protect their safety."
A U.S. law gives parents control over what information websites can collect from their kids.
The Children's Online Privacy Protection Act, or COPPA, imposes certain requirements on operators of websites and online services -- including social media sites -- so that personal information from children under 13 is not collected, disclosed or used without parental consent.
For instance, a page on Facebook indicates that the social platform "requires everyone to be at least 13 years old before they can create an account. ... Creating an account with false info is a violation of our terms."
The page provides a link on how to delete an account if your underage child created one, and it provides a form to complete if you'd like to report an underage account.
"It's not technically against the law for kids to sign up for an app that is supposed to be for older than 13. Under COPPA, all that's needed is for parents to provide consent for companies to track the data attached to that account. Unfortunately, privacy policies come with so much gobbledygook, it's really hard for parents to understand what they're agreeing to," Knorr said.
"A lot of parents believe that the reason why the age is 13 is to help protect kids' safety, but really the reason why the age is 13 is because most social media shares data, and they actively mine data, and they're not allowed to do that for users under 13," she said.
In order to help protect your child's safety, "the big thing is having a conversation with your child about social media use early and often and being aware of what they're doing, and having filters and using strict privacy settings while you're still monitoring their social media frequently," said Dr. Candice Dye, a pediatrician at Children's of Alabama and assistant professor at the University of Alabama.
Tell them, " 'if you don't know somebody and they ask to be your friend, you don't accept that. If somebody's doing something on there that is offensive, then you unfriend them,' and then talk about general security things like 'passwords are private, and you don't need to write them down or share them with others,' " Dye said.
"It's just about having those conversations with them and setting those boundaries and making room for the conversations to continue," she said. "You want them to feel free discussing things with you as they come up."
Though privacy and safety are important, Knorr views screen time itself as being among the biggest concerns when it comes to children signing up for social media.
"Many parents find that their most pressing concern about their kids getting social media is not really the safety and privacy but the 'time suck' aspect of it," she said. "Of course, more time spent online does lead to more potential risk. So that's another really good reason to help kids try and limit how much time they're spending."
For children and teens, 5 to 18 years old, the American Academy of Pediatrics recommends that they do not sleep with devices in their bedrooms, they avoid using devices for an hour before bedtime and they avoid using devices during family dinners.
The academy also recommends developing a family "media use" plan that includes consistent limits on how many hours of screen time are allowed per day while allowing for at least an hour of daily physical activity and an adequate eight or more hours of sleep.
The group warns that too much screen time can place your child or teen at risk of obesity, sleep problems, cyberbullying and negative performance at school, among other concerns.
"I see many adolescents whose feelings get hurt by seeing photos of a date with another boy or girl. Some peer groups use social media to hurt each other," Friedman said.
"Monitor your child for safety," she said. "Certainly bring up the issues that involve safety."
However, she said, those other potential risks also should be included in family discussions.
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