At WordCamp Rhode Island 2016, I ran the Contributor Day workshop. Before we got to work contributing to core, I gave a short presentation about how the WordPress development process works, and introduced them to the tools they would need to be familiar with.
I followed the Trac tickets that the participants became involved in. By my count, 5 first time contributors were credited in WordPress 4.7.
Congrats to all of the first-time contributors from WordCamp Rhode Island!