Your Custom Audience from your website will update automatically as people who fall within the rules you specified for your audience navigate to the pages on your website that have the Facebook pixel.

For example, if you've set your Custom Audience to only include people who've reached the "Add to Basket" page of your website, it'll automatically add people who navigate there to be part of your audience. If you didn't set any rules, then your Custom Audience will automatically update to add anyone who visits your website.

Bear in mind that it takes 24 hours after you create your Custom Audience from your website for it to start collecting data.

* Nguồn: Facebook