There is no cardinal black and white rule about this. Any number of things could occur at the time of the hearing: 1) the Respondent could show up and ask for a continuance to find an attorney--the court could deny or grant the request; 2) the court could let the Respondent speak and make a defense at the time of the hearing; 3) the court could refuse to let him file anything because of the delay in filing a response. In a nutshell--it ultimately depends on two things: 1) what the Respondent will say and/or do at the time of the hearing; and 2) what the judge is in the mood to do. Again, there is no hard-fast rule on this.
If you can't afford to have an attorney represent you, keep in mind that there are attorneys in your area (Bay Area) who provide free consultations as well as legal coaching services.
PLEASE READ--before emailing, commenting or calling: As a rule, I do not respond to "comments" that are designed as follow-up questions to the originally-posted question. I specifically do this as to avoid creating any confusion to the originating author of the question and to prevent any attorney-client relationship from forming--as this is not the goal or intent of this attorney or the Avvo creators. Further, I am only licensed to practice law in the State of California; therefore, any information provided in this answer is intended for application in California. Second, the information provided in this answer is solely intended to serve as GENERAL INFORMATION, and, at most, to serve as a catalyst for discussion between you and an attorney. Under no circumstance, is this information provided in this "Answer" intended to be construed as legal advice--and is not to be considered legal advice for any purpose. If you wish legal advice, then it is recommended that you contact a licensed attorney in your area to discuss the particulars of your case. Only by engaging in a meaningful discussion with a licensed attorney, can an attorney then provide you with legal advice.
I have handled restraining order hearings in San Francisco on several occasions. I do not believe you are required to file a formal response to the charges. However, I file a response on the judicial council form denying all of the allegations that should be denied and explaining any that need to be explained. You need to hire a lawyer to put a case together for you.