It really depends on the kind of popup and trigger you set:
– If you create a popup with an “exit intent” trigger, you should set “1” page view minimum because you want to give the opportunity to every visitor leaving your website to ask for a reminder.
– If you create a button widget (little button on the bottom left or right of the page) or an accordion popup, you can put it on every page from the first page view to the last one. This gives the opportunity to your visitor to click on it at any time without bothering him during his visit.
– If you create a popup overlay that will cover what the visitor is reading (a part of the page of the full screen), you should generally set at least “2” pages view minimum. This is because this kind of popup will convert visitors that have spent enough time on your website to know if they’re interested in what you offer or not. But it’s up to you to define if the best time to display this popup is the 2nd page, the 3rd or the 6th, depending on the average number of pages view per visit on your site.
However, you can also choose to display a modal popup right from the 1st page view, but set a time trigger (15 sec or 30 sec) or scroll trigger (75% scrolled) which will assure you that the visitor saw enough of your site to know if he’s interested in what you offer or not.