But I don't have a big channel to let people know that the challenge is starting.
Here, Reddit, Twitter, other social media.Problem with this is that Reddit users are gonna flame me, but I can always just post when it starts on reddit and give you guys a small heads up. People here can vouch that I am legit and not some random scammer 
I hate Reddit for this exact "mob rule" mentality that it has. But if you link to your old puzzle and this thread, then that should convince anyone that you are for real, having already given away 0.01 BTC. (Thanks again! )Sure, I might PM you when the date is closer.
Sure thing, but as I say, I am far from a fount of knowledge on such things. A public thread asking the whole community for important dates would definitely provide you with a lot more material.