How Long Does It Take For A UTH To Heat Up

[mrshawt]

also is it ok to peel the white part off and stick it on the tub and it has been a day and the heat hasnt gone through the tub

Better idea so you can reuse the UTH and move it around:

Remove white paper backing. Cover stickiness with foil tape.
Then, just use more foil tape to attach the UTH to the bottom of the tank.

It should have warmed up by now. Is it on a thermostat or rheostat? What are the temps reading?