AdSense, Amazon, Apple II / iPod / iPhone / iWatch, CNN, JavaScript, Netscape, Netflix, PayPal, Roku
The critical window isn't when something is first possible (e.g. when the first product appears), but when the combination of technical abilities, component price points, and market characteristics intersect to permit success.
To use a physical example, the iPod and iPhone were great products, but they were hits because they launched with the features they did, at a specific point in time, at a specific price point.
We know that potential for success infection point existed then, because they did build a working device and achieved success.
Consequently, if they had not completed those devices when they did (say, +20% time), another device could have achieved their success.
Maybe nobody on the planet existed other than Apple who could do it... but the possibility was provably there.
Or in simpler form: Netflix was far from the first streaming video service. They were the one who launched with the right features at the right time.
Nobody cares if you catch a small wave perfectly. What matters is catching the best wave of the day, in the brief window you have.