There should be a 95% (or higher) likelihood of finding a winning version.
You should wait until there are at least 100 conversions.
However, as we mentioned, there's no "one size fits all" approach when it comes to defining a concluding point.
In a recent "unwebinar" with our friends at Unbounce, our marketing director, John Bonini revealed that we typically run our tests for anywhere between 30-90 days, depending on the amount of traffic that we're driving to the variants. For example, if you're driving millions of people to your pages, it's likely that the time between launch and conclusion will be far shorter than a website that is only bringing in a couple thousand views a day.
While there are "statistical significance" calculators out there to help you determine whether or not it's time to call it quits, we urge you to proceed with caution.
I, too, was excited about the functionality of these tools upon discovery, however, after reading into a bit I found that sources were reporting that these tools often call tests too early, putting you at risk of disrupting the legitimacy of the results.