Install timing belt around lower half of engine, install timing belt cover, and install crank pulley.
You want the #1 piston at TDC (crank pulley lined up with the "0" mark on timing belt cover). It must be at 0 (TDC) not 10 degrees BTDC or ATDC or whatever the hell you tried to set it at.
Both camgears also must be at TDC (hole in camgear lined up to the mark on top of the backing plate).
Install belt around right camgear (front cylinder head). Make sure the belt is tight.
Install belt around left camgear (rear cylinder head).
Make sure the belt is tight then tighten up the tensioner.
Rotate crank from TDC to TDC (0 to 0) and check alignment. Crank and both camgears should be at TDC. If not you get to do it all over again.
Heres some instructions straight out of a factory repair manual:
http://www.yotarepair.com/Timingbeltinstructions.html
Theres no instructions for a 3VZ-FE, but you can follow one of the other ones.