I have to sign a contract on thursday, but I don't want to set myself up. (USAF ?)?

I just found out a few hours ago that I'm scheduled to leave for BMT on February 9, 2010. I won't be able to take the DLAB right now because of my 2 yr. old asvab scores (trust me when i took them i didn't even have the thought of enlisting on my mind). The only way i'd be able to take the DLAB would be if i were discharged and then allowed to retake the asvab for a shot at a high enough score that would enable to become a Crypto Linguist. It's funny because they have me for electronics (space systems and intel ) and I don't know ANYTHING about electronics and i really scored high in this section. (WTF i was probably guessing!) But im REALLY good with math and paragraph comprehension, word knowledge.. etc. Linguistics would be like a dream job for me. But my recruiter's telling me to just go in.. and then cross-train. (becaus of my home situation, i need to get out asap!!!) He says once im in i won't have to retake the ASVAB. So basically what I'm going to do is sign the contract (?)[probably just saying that i will voluntarily leave on that day in february under the electronics field.. blah blah], go to basic training and talk to the job counselors out there (?). Sound good? I've done plenty of research but I haven't read up a great deal on cross-training. If you have any (mature) input, I would appreciate it. I'm open to suggestions.