This story is part of Apple Event, our full coverage of the latest news from Apple.

The next version of Apple’s mobile operating system, iOS 15, will arrive on Monday, Sept. 20. (Here’s how you’ll download and install iOS 15 when it appears.) Apple revealed the date during a launch event earlier this week, at which the tech giant also unveiled the iPhone 13, new iPads and the Apple Watch Series 7.

While the new software for iPhones (and iPadOS for iPads) is full of brand-new features like the ability to FaceTime Android owners, store your driver’s license in your digital wallet and some major Apple Maps upgrades, you might want to consider waiting an extra week or two before installing iOS 15.

Sure, you can run headlong into the new operating system and play with all the new features as soon as they’re available. That’s the fun of it, right? But there are some good reasons that might stay your hand from clicking the Update button when it pops up.

Why iOS 15 won’t be perfect at launch

The beta release of any version of iOS is intended to help developers identify and squash bugs before the operating system becomes widely available. However, some bugs are likely to slip through to the launch version. Just look at last year’s general release of iOS 14, which reverted users’ default browsers and mail apps every time they restarted their devices, among other glitches.

Bugs and issues just like that have cropped up in the iOS 15 and iPadOS 15 betas, and could still be a problem in the initial general release. And even if these issues don’t completely stop you from using your iPhone or iPad, the bugs will still likely be annoying and disruptive.

Based on our experiences testing the iOS 15 beta, the third build was worse than the ones that came before it. Apps constantly crashed for no reason, and the keyboard would randomly stop working on the iPad Pro. Again, Apple’s development team likely caught and addressed most of those bugs. But if you download on Day 1, you’re setting yourself up to be the live version of a beta tester.

How long should I wait before downloading iOS 15?

Going back to the iOS 14 example, the issue with default apps was taken care of a week later. That’s the window you should look for: Wait a week, maybe two if you want to be super cautious, and then download the new iOS. By that point, most of the early bugs in the overall OS and individual apps should be worked out.

Don’t wait too long, though

While a certain amount of caution can help you avoid headaches, you shouldn’t be overcautious. Delaying updates to your operating system for too long can also leave you vulnerable to security flaws. Any operating system updates that are related to security issues — like the iOS 14.8 update released earlier this week — are important to install as soon as possible to keep your device secure.

The launch of a new operating system like iOS 15 rarely falls into that category, but it’s an important distinction to make. Whenever you decide to update to iOS 15, make sure your device is ready first. It’s difficult to revert back to the previous operating system, but it is possible.

For more coverage of the iPhone 13 event, check out everything Apple announced and why the biggest iPhone 13 feature is its trade-in offers.