Couldn't you have applied for her

when you applied for your greencard as she is your child and a minor? I am no immigration expert,but if you wait till you are a citizen then apply for her, she will be around 14 years before she can get an immigratn visa. If you file form I-130, the wait time is only one year. So I suggest you file I-130 now.

check the INS processint time at: http://www.shusterman.com/cgi-bin/ex-s-link.pl?egov.immigration.gov/cris/jsps/Processtimes.jsp?SeviceCenter=Vermont