How much jail time will I get for not completing 40 hours community service on time if the judge wont grant me an extension?

I am not able to answer this question without knowing more about the case. Do you know if the probation department is filing a violation of your probation? It appears as though you made an appropriate response, but you should try to get some hours in as quickly as possible. You should try to put together a reasonable plan for completing your community service in a timely manner. If you have been otherwise compliant and cooperative with your probation, then you may be able to avoid jail time. My best advice is to work with your probation officer and perhaps more importantly, consult with a criminal defense attorney.

This question is best asked to your attorney. In the meantime, take time off work and work full-time getting the hours completed. If you make completing the hours a priority, you should be able to get the hours completed within a couple of weeks. It would be hard for a judge to justify imposing any jail time if you have completed the hours. On the other hand, any uncompleted community service hours are typically concerted back to jail time, with the possibility of an additional sanction for failure to comply.

That's impossible to answer without intimate knowledge of all of the factual surroundings. Speak to your lawyer.