Google has started disabling Flash and displaying HTML5 content instead on certain websites for a small number of people using its Chrome browser. People can still explicitly permit Flash to load on the affected sites — which are the top 10 that use Flash.

Google has deployed the change for half of the people who are using Chrome 56 beta, which rolled out yesterday, Google technical program manager Eric Deily wrote in a blog post.

Then, “in the next few days,” Deily wrote, the feature will be active for 1 percent of users of Chrome 55 stable.

And by February 2016 it will be live for all users in Chrome 56 stable, Deily wrote.

This week’s release is on time. In February Google said the HTML5 by Default program would go into action in the fourth quarter of this year, and in August Google said it would effectively happen in December.

The idea is to lessen the dependence on a web component that can cause a drag on CPU and memory usage and shorten battery life as a result. Flash also has a track record of security issues.

But it appears that Google chose to push back the timeline of Chrome showing HTML5 instead of Flash for all websites.

See, Google doesn’t want to ask users for permission to start using Flash for every site. In January, Chrome will do that when people visit sites they haven’t visited before. Google will do that more and more based on where sites fall on what Google calls the Site Engagement Index, which is a way of evaluating website usage. The end of the road will be in October 2017, at which point all sites will ask people for permission to run Flash.

It turns out that the original plan was to do that in July 2017, not September or October, Google technical program manager Anthony LaForge wrote in an email that circulated on the Chromium developers mailing list earlier this month. As a result of the delay, developers will have more time to switch content over from Flash to HTML5.