I'm late for pick-up. I'd like to call my daughter to tell her to wait in the playground, but she's still at primary school and doesn't own a phone - not yet, anyway.
If I channel Bill Gates I'll make her wait until she's 14. If it's good enough for his kids, it's good enough for mine.
Then again, maybe 11 is the magic number? Research shows that's the age that two-thirds of Kiwi kids get a phone.
But already children in my daughter's class are getting phones and she's nowhere near 11.
"Every family situation is different. Every need is different," says Taino Bendz, founder of PhoneSmart, a start-up which works with families to reduce screen time.
"The most important thing is to talk about it as a family. Do you need to have constant connectivity? Don't just do it because other people are doing it."
Psychologists say we should forget about age and think about the child's maturity level.
Firstly, is your child forever losing things? If they can't keep track of their school jumper or sports kit, it doesn't bode well for an expensive item such as a phone.
Can the child be trusted to use the phone responsibly? A phone is also a content creator. Text, photos and videos can be widely distributed. Will they refrain from embarrassing themselves or others? Do they understand what cyberbullying is?
"The moment a child owns a mobile phone it can be a challenge to monitor what your child is accessing online because it's such a private technology that most keep literally close to their chest," says Simon Legett, director of the market research group Childwise.
Lending rather than gifting a first phone is a good way to retain some control over how a child uses it or there's the option of getting a 'dumb' phone rather than smart one. That way it can only be used to make calls and texts, not connect to the internet.
"I bought each of my kids one of those basic flip phones," says my friend Susannah, a mother of two young teenagers.
"They totally hated me for it but at least I knew they weren't falling down the rabbit hole of social media."
Parental controls can be helpful to ensure smartphones are used sensibly. Apple has a feature for its iPhones which can set time limits and provide statistics and reports on usage. On Android phones, parental controls can be activated through Google's Family link.
"We gave our kids phones at a very young age, about nine, and this is because they took public transportation to school on their own," says Lucian Teo, trust and safety outreach manager at Google Asia Pacific.
"But what we did was turn off everything. They didn't have a browser, YouTube - it was basically a communication device with a GPS tracker."
Bendz believes parents of teenagers need to think carefully about how to handle their children's ownership and use of their device.
"It almost becomes the forbidden fruit if we try to put in surveillance apps, or close off the App Store, or set too many rules. I believe in talking to our child about it. 'OK, there's a lot of information out there. What would you use the phone for?'"
Common advice for parents is to draw up a family contract to set rules around phone use and behaviour with consequences for rule breaking, such as losing access to the device.
Getting kids to pay a percentage of their pocket money towards the phone and its bills can also ensure they have some skin in the game.
There should be no phones before homework, at the dinner table or in the bedroom. But even with the best intentions, children can quickly get addicted to their screens.
Plenty of parents can tell stories about their kids staying up half the night on their phones - some even attempt to get violent if their phones are taken off them.
"He had his head buried in his phone all the time," says Jackie, a mother of four, who's had a struggle handling her 14-year-old son's phone use.
"Even when we'd leave it charging in the lounge overnight he'd sneak out and retrieve it. We have had to resort to locking it away at night so he'll get some sleep."
As adults we can do a lot to shape our kids' behaviour with their devices.
The way my husband and I use our phones at home is appalling. We check them constantly from first thing in the morning to last thing at night. How can I expect my children to behave any better?
"Mum, are you paying attention?" my daughter often scolds me.
No, not enough.
For 2021, I need to practice what I preach. As for my daughter? I'd like to hang on until she hits her teens. Wish me luck.