If you are in warrant status you need to take a copy of the citation to the traffic clerk's window in Van Nuys and get yourself put back onto calendar so the warrant will be removed. You do need to be there at 830. The traffic clerk will put you on calendar.
I hope you printed out your extension when you got- I assume online. Bring it to court. Get there early and make sure you are on calendar. If not speak to the bailiff in the the Court or clerk there- showing them your extension. They should be able to have you ticket sent up.