We were the first to report that the plan for Sting was to debut on Raw. The latest Figure Four newsletter is also reporting that the plan would be for Sting to debut on Raw. As far as WrestleMania goes, the plan was to show a video to hype his debut. It would be similar to what they did for Goldberg in 2003 at WrestleMania 19. They played a video for Goldberg at the show and then he made his debut the next night.
Some other non-Sting notes:
Expect the announcement for WrestleMania 32 (it will be in Dallas) to come around October.
There are tons of people in different parts of town getting “YES” chants started. There will be a massive pop tomorrow when/if Daniel Bryan wins the WWE championship.