TF3D should start automatic. If no user action is recognized after 30 seconds S2U2 will appear, and after another minute (aprox) device goes to standby, after standby (give it some seconds in standby) TF3D will restart. On power key device goes to standby, too.

It’s important to uninstall any previous versions, before installing the new one.

http://forum.xda-developers.com/showthread.php?t=450556