At what RPM's Should my Vtec kick in
 

I have a 2002 honda accord ex manual with a ulev engine

As low as 2000 rpm. The ECU monitors several sensors to engage VTEC and depending on engine load and other factors, it will engage at different rpms every time.

I second that^. VTEC in our cars is for fuel efficiency, not power like it is in Prelude's or Integra GSR's. You won't feel it kick in like you do in a Prelude or a GSR.