Your wife's naturalization if it happens in Oct 2012 would leave just 3 months to your daughter's 18th birthday, but with an already-approved I-130, I-485 approval is possible in that time frame.
However, you need to make sure everything is done right so there are no delays introduced by your mistakes. Schedule a consultation with an immigration lawyer (one who has experience with I-485 interfiling) a few weeks before your wife's naturalization interview, explain the situation to the lawyer and ask the them to prepare the I-485 interfiling request and tell you what documents you need to send with it (that will include but is not limited to a copy of your green card and I-485 approval, the daughter's I-485 receipt, your I-140 approval notice if you have it, daughter's birth certificate, your marriage certificate and wife's naturalization certificate). The interfile request should include a paragraph asking them to expedite the I-485 because your daughter's 18th birthday is on January xx, 2013 and she would lose eligibility for citizenship under the Child Citizenship Act unless the I-485 is approved before that date.
Then gather the documents and wait for your wife to become a citizen. Once that happens and she gets her naturalization certificate, go back to the lawyer ASAP with it so he/she can finalize and sign the letter with the current date and mention the date of your wife's naturalization, have the lawyer double-check your documents, then take the lawyer's letter (with lawyer's letterhead) and send it to USCIS (don't have the lawyer handle the case all the way to the end, as that would be more expensive; you only want a couple of consultations to prepare the letter and check your documents then you'll send in everything yourself and handle it from there).
Also make sure your wife isn't missing any information or documents at the naturalization interview. Even though she was not the primary applicant for her green card, they may ask her some questions about your green card process, such as who sponsored your green card, when did you leave them, and what other job you took after leaving them. And make sure she has a copy and the original for both of your children's birth certificates (but she shouldn't show them unless asked).