It depends on how you're trying to bring them. Did you petition for them as a U.S. citizen? If so, check the priority date on the receipt notice you got back from the I-130. The current wait time for this kind of petition is about 12 years, unless they're from Mexico or the Philippines, in which case it will be longer. You can look at the Visa Bulletin (http://travel.state.gov/visa/bulletin/bulletin_5856.html) to see which petitions they're processing right now, and that should give you an idea of about how much longer it will take.
The information offered is general in nature and not meant to be relied upon as legal advice. No client-attorney relationship is created through this information. Please consult an attorney prior to making legal decisions.
However long it takes for the priority date to become current. The movement of priority dates cannot be predicted.
For the latest visa bulletin see http://www.engnishimura.com/priority-dates/current
J Charles Ferrari Eng & Nishimura 213.622.2255 The statement above is general in nature and does not constitute legal advice, as not all the facts are known. You should retain an attorney to review all the facts specific to your case in order to receive advise specific to your case. The statement above does not create an attorney/client relationship. Answers on Avvo can only be general ones, as specific answers would require knowledge of all the facts. As such, they may or may not apply to the question.
It could still take awhile, but at least they're in the queue. Make it a habit to check the visa bulletin to track when their priority dates become current.
(626) 771-1078 Los Angeles Attorney Theodore Huang, Esq. This is not legal advice. No attorney/client relationship is established. Attorney Huang is licensed in MD; practice limited to federal law.