We completed the k-1 process, my wife is here from Brazil, we got married and applied for her social security number. how long can we delay applying for her green card? reason is... we just don't have the money right now.
Ideally you should do so before her K1 90 days authorized stay expires to ensure she doesn’t accumulate any unauthorized stay presence. Of course an unauthorized stay presence will not prevent her AOS petition from being approved when you eventually apply for her GC (assuming you decide to wait past the 90 day mark), it just means she’s deportable starting from day 91. My recommendation is borrow money if you have to, and file right away.
We Americans don't like anyone unauthorized living in the US, even an IR of a USC. Your wife loses her status on day 91 from her K1 admission. Your best bet would be to find all possible ways to fund the AOS process and mailed to USCIS prior to day 90 deadline.