Thursday snapshots arent very well attended most weeks, I'm pretty sure alot of people dont even know they exist.
If I announce on country channel I always get a couple of new people along, and thats just one country on one map. I know most CMs will announce on 200 before they start, but alot of people (most?) dont tune 200.
How about having the announcement for any special event on the MOTD for all arenas on the day of the event, not the full SEA MOTD but just a brief summary? Then at least everyone will know that there is an event on. Follow that up with a all-country announcement 60mins and then 30mins before event start and you will surely get more interest.