Internet based use of IPv6 was “officially” started on June 8, 2011, which was dubbed World IPv6 Day. Over 1000 Web sites and services, including Google, Yahoo, and Facebook, participated in a 24-hour test of IPv6. The event was seen as a great success. On June 6, 2012, the next phase of IPv6 deployment was initiated. This new and ongoing project is called World IPv6 Launch. It is an effort to encourage ISPs and networking equipment manufacturers, in addition to online services, to permanently enable IPv6 support in their products and services.
Since June 6, 2012, there has been a fairly consistent increase in IPv6 traffic. With this current rate of adoption, nearly universal use of IPv6 should be accomplished by 2018. This switch over to IPv6 will not eliminate IPv4. In fact, it is likely that pockets of IPv4 will continue to exist for a decade or more beyond the point of the Internet switchover. This will mostly be due to legacy hardware that continues to function and for which there is no pressing need to replace. During the transition IPv6 to v4 gateways will be in widespread use, and the use of such a translation device will allow legacy IPv4 networks to survive long after the majority of online traffic is IPv6.
There are many excellent resources on the progress of the transition, and I encourage you to explore a few of these: