I have seen that doing JROTC may earn you up to E-3 upon enlisting. But, I have a question.
Let's say that I did Air Force JROTC, and then enlisted in the Army. Would the same E-3 thing be applicable?
In answer to your question: today, if you do three years of JROTC, the Army, Navy, and Air Force will enter you as an E-3. The Marines will give you E-2; E-3 is reserved for that one honor graduate out of the training class.