Its hard to give you a precise answer since the times jump without reason (become current or retrogress). It could be 8 months, sooner or longer. Daughter ought to be ok since her age may be frozen in time due to a law called CSPA but this law now is in flux since 3 cases being reviewed by the US Supreme Court so not certain yet.
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.