If you haven't checked your record already to make sure your ADULT record is clean, it's sort of a crap shoot. Sometimes juvnile violations are actually expunged, and sometimes they hang around to cause trouble later.
If you get rejected for your CHP, you're going to have to hire a lawyer to get the Court of Record to remove those records from your adult profile, and it's going to cost you a few grand to get a "clean record" again. Yes that is correct--YOU have to pay to make the Courts do their job if they screw up and don't do what they are supposed to and it causes problems.
So there is no real way to answer your question unless you do a background check yourself (or have a lawyer do it for you) before hand...