Oh man, I just love this so much! Frankly, I love the Chobosaurus name! It adds the funzy aspect of it forth quite well. Some people might be a bit confused and maybe not quite see the point of it, though, but there will always be whiners
(PS: Realized just now that it might be a bit misleading calling it a League, since then people might expect it to be an event that lasts for several days/weeks. It could be called a Tournament instead, for instance?)
Forming teams and practice is really good for preparation, at least! But if it's for the sake of PR, I reckon it'd be adviced if f.ex. MadiNho or any other streamers were to practice a lot of 3v3 with his team and write "Practicing for the 3v3 Chobosaurus League 2019" on the stream. Then people might ask questions, and the balls keeps rolling. If all clans involved were to do that, however I think rumour might spread a bit quickly.
Furthermore, I think it's important to be out early with information on official sites (i.e. TL.net and reddit). However, be sure that the information is as complete as possible when you do. The more you have to update the information, the more likely it is that people won't be able to keep track. In general, when organizing events, imagine handling a kindergarden. That's the attention span and level of organization you have as a reference. I don't mean that in a rude way, but it's simply the nature of organizing events in e-sports (often in anything else too, but e-sports is my main reference).
There's also bound to be a lot of trouble with lag. Making some clear ground rules prior to the tournament would be important. Even if it's an unfair rule, a simple rule may often be the best. That way, you won't have listen to all the angry arguments, but just say "you accepted the rules when signing up, quit whining". And I think team games in particular have a lot of strong personalities who'll go apeshit over nothing. I think Rus_Brain recently organized an event where he simply stated something like; "If there is lag, the one closest to the Russian standard will get the win". Many would call it unfair, but it's better for the tournament overall to just cut your losses, and keep the tournament moving forward. If not, you'll have people waiting forever since they're arguing, and then people start going afk because they were waiting, and then OTHERS are waiting and....you get the point
I think in general, all these things are much less a problem thanks to the teams coming strictly from ReD, iRk, and ReV. Seeing as we're all on very friendly terms and overall have similar latency (roughly), I think it won't be nearly as much of a problem as it could've been if it was open for anyone to play.
As for streaming - I'm assuming Vincent will be streaming replays? In which case, how does he choose which matches to cast?
Have you considered seeding, so that the strongest teams aren't knocked out right away?
Will it all be on the same map? If not, how early will the map pool get out?
Lastly, there will never be a date that works for everyone. Some teams, no matter how strong, will eventually be left out this time. It's extremely unlikely to have all our cream-teams play on the same day. So I think when setting a final date, just be firm - ask a bit around, and based on what you hear you just set a date you think is best. And then people will just have to work around that. Plus, it'll be an extra reasons to arrange it more times, in order to give everyone a chance to participate
And there I go building walls with words again. Trump really should hire me!
Not sure if all of this is what you're looking for, but I figured I'd just spam it all out there and then you do with it as you will <3
Really, really love this initative and would like to help out and support it as much as I can!
(This is your baby, after all <3)