When Did the Anthropocene Start?

Many scientist have talked in terms of specifying a new geological period they feel should be labelled the Anthropocene as humans have now become, by far, the biggest agents for change on the Earth (reportedly causing more extinctions than the cosmic collision that did for the dinosaurs, generating substantial climate change and producing mountains of plastic). Two British authors (Simon Lewis and Mark Maslin) have now claimed in a book, 'The Human Planet: How We Created the Anthropocene', that the era really begins with the European (largely Britain, France and Spain) colonialism of other parts of the world (https://www.theguardian.com/science/2018/jun/10/colonialism-changed-earth-geology-claim-scientists). Their argument is based on the fact that the effects of such colonialism are said to be detectable in both the rocks and the air. The actual start of the era is, I feel, somewhat arbitrary. We could take as a start the time when large sections of humans on the planet gave up the hunter/gatherer life-style, that our biology seemed to have adapted us for, for an Agrarian-supported life . You could also argue that it commenced with the Industrial Revolution in Britain. Perhaps more pertinent is the question, 'when will the Anthropocene end?'