The first was on 2016.
The second on 2017.
Will the third be on 2018 or before ?
This one is the last one.
In the dashboard (https://dashboard.stellar.org/) , we can read that the total XLM is 103,06 B XLMs and only 5,84 B XLMs are distributed (for 10,59 B XLMs available).
I mean it's the last free XLM distribution for BTC. There will be more free distribution in other ways.
Actually I still don't fully understand stellar lumen project and potential for future, I knew stellar at 2014 and then change name to lumen, I only know that they giveaway some lumen to btc holder for free , maybe team hope more people using lumen , but all of them not just dump for free $$, then lumen price drop