In our experience they do not request jail time for a first offense on graffiti. They do take a hard stance in that they often offer no plea bargaining so that you may end up with a criminal record (maybe even a felony criminal record) and community service. I don't know the circumstances of your arrest, but you may have defenses or mitigating factors to help you avoid the harsher aspects of the case. The goal would be to try to end up with no criminal record a small fine and some community service. Please feel free to give me a call if you would like a free consultation at my firm.
Since this is a first offense it is very unlikely that you will do jail time. You will most likely get a probated sentence and be placed on probation. If you successfully complete probation you will not go to jail.
As far as the degree of offense you would need to speak to an attorney in your jurisdiction.
In Texas Criminal Mischief offense levels are based on the monetary amount of damage.
Making Graffiti and Possession of Graffiti Instruments are both misdemeanors and although you face up to one year in jail it is very unlikely that you will do any jail time. Criminal Mischief can be a misdemeanor or a felony depending on the degree. Criminal Mischief in the Fourth Degree is a misdemeanor but in the Third Degree is an "E" felony. The difference is whether they can prove that the damage exceeded $250. Either way it is unlikely that you are going to jail. You may have to pay for the damage and you should, of course, spaek to a criminal defense lawywer as soon as possible.