The first hearing is probably an arraignment; the type of hearing is probably described on the summons. He can ask the criminal court clerk about the process for petitioning for a court-appointed lawyer. Odds are there's an affidavit he must complete describing his income and assets, that is reviewed by the court.
Note that for some minor offenses, particularly where the prosecutor stipulates that there will not be a jail sentence, some counties won't appoint lawyers. I don't know if that's the case in the county where your son is charged.

