Microsoft opened up the waitlist for its Bing AI preview last week, and after 1 million people signed up in 48 hours the company is now explaining why it’s taking some time to unlock it for millions of people.

Microsoft is testing the Bing AI service in 169 countries around the world, and the company says it’s prioritizing people with Bing and Edge as their default search engine and browser, as well as those with the Bing mobile app installed. That’s why Bing briefly rose to the top of the App Store last week.

“If you’re on the waitlist, just hang tight,” explains Yusuf Mehdi, Microsoft’s head of consumer marketing. “As we said at launch, we intend to scale to millions of people beginning in the coming weeks. We’re only one week in!”

The current Bing AI preview is also limited to Microsoft Edge right now, but there are plans to expand beyond Microsoft’s own browser. “Over time we intend to bring it to all browsers,” says Mehdi.