I have my first hearing for my first probation violation, its not the sentencing hearing yet, but I'm wanting to know if they are going to put me in jail at my first hearing, or if they wait till sentencing?

What state are you in and is this misdemeanor or felony probation?

The hearing is to decide "IF" they are going to put you back into jail. Normally at least here, there are not two hearings, you were already sentenced, this merely modifies the sentence you already had.