I've been on SE site X for two years and six months, call it thirty months, and haven't gotten a Yearling badge. No surprise, since my reputation is less than 200.
In month 31, I "get active" on the site and my reputation starts to climb. I get a first, and then a second Yearling badge within days of each other. Specifically, I get these badges on the days that my rep rises past 200, then 400.
So did I meet a "dual" requirement? That is, I got badges for the lesser of the following two numbers: 1) the (completed) years on the site and 2) the whole number representing the quotient of the increase in my reputation divided by 200?
And if my rep on site X is now over 600, does that mean I'll get my third Yearling badge on my third anniversary on the site?
(There have been several other questions on the Yearling badge, but the protocols regarding it appear to have changed over time, so I haven't seen an "up to date" answer.)