You could say it started with ImageNet 2012 where AlexNet showed that deep networks were a newly promising area of study - however the actual performance of AlexNet was very very far from human performance. I tend to say the revolution started at ImageNet 2014 with VGG/GoogLeNet, the first human-caliber performances. Or you could say it was ImageNet 2015, when the first ResNet had better-than-human performance.
