Those are some good prizes!
Less than 11.6 million bets left until 4 billionth bet, and since around 3,000 bets per minute are made currently, it means that 4 billionth bet will be made within the next 64 hours. But of course the users' activity can intensify when we are closer to the event, so I won't be surprised if ti will happen tomorrow.
I have a question regarding the rewards distribution. If the very first valid bet will be, say 4,003,000,000, will it be rewarded with 0.02 BTC instead of 0.1 BCH, and will all the other rewards be shifted downwards?
First valid bet will be rewarded with 0.02 BTC and I doubt that there will be 3 million invalid bets since it's very easy to meet requirements.