It does not really matter how long the I 130 takes as long as it is completed before the the PD is current.
And the longer it takes usually the better if she has or will have children, does she have children?
They do not seem to rush the I 130 knowing it does not really matter.
Not sure where you saw the 10-15, but basically she files the I 130 and then basically forget about it, maybe check in 2040 and see how they are going.