Timed Popup
A popup that appears after a fixed delay, such as 15 or 30 seconds on the page, using time spent as a proxy for interest.
A timed popup waits a set number of seconds after page load before appearing. The delay separates visitors who bounced immediately from those who stayed, so the ask reaches people who have at least started reading. It is the simplest trigger to configure and the easiest to get wrong.
The right delay depends on the page. Fifteen seconds on a long article barely covers the introduction; the same fifteen seconds on a short landing page may land after the visitor has already decided. Look at average time on page in your analytics, set the delay somewhere before the point where most sessions end, then test a longer and a shorter version.
Time alone is a weak signal, since a visitor may be idle in another tab. Combining a delay with a scroll threshold filters out idle tabs. On mobile organic entry pages, be conservative: a full-screen modal that fires a few seconds after arrival is close to the pattern Google's intrusive interstitial guidance describes, so use a slide-in or a longer delay there.
See it in practice