Can I get out of the Navys DEP program?

Okay. I joined the Navy in September of 2007, and now its March 2008 and I have decided that i dont want to go. I want to start college right when i get out of high school in May. Also, i do not think that the navy offers anything to do with cosmotology and thats what i am looking into going in. I need to know what would happen to me if i told my recruiter that i didnt want to go. I was told that i need to write a letter to the commander and maybe he would accept my request. I was also told that if he denied it then i would be sent on 8 years active duty, which is how long my contract is. I would be sent out on September 3rd and i need to know when i should send my letter. Help anyone? thanks.