Help!!! What do I do?

My AF recruiter called me today and told me that somebody backed out of DEP and I can ship out tomorrow for basic training. I told her I want to wait for my original ship date which is January 26. She said I had no choice. I could either back out of DEP or ship tomorrow. She told me this is my new ship date. Can they do this? What do I do? I really don't want to ship tomorrow.