Good question.
In the reward 3 example of 5 million gacha draws divided by 100k participants would suggest that those 100k participants drawn the gacha 50 times each. Assuming everyone drawn 5 a day, that would make it 10 days. Today, I drawn my 50th gacha, so it can possibly be today?
P.S. I tried messaging them on twitter a while ago about an approximate release date, but they didn't reply.