H1b change in employer & new H4 stamping

The current H1b visa stamp on my passport is from previous employer and is valid till Sept 2017. Now with my new employer i have approved petition till 2019.
My vacation plan was to travel to india in Dec 2017 and return in Jan 2018 and during this period get H4 stamping for my spouse(This will be her 1st H4 stamp).
Now I just learned that even if there is a change of employer, I will not be able to book a personal interview(my plan was to go for interview in Dec with my wife) as I am eligible for drop box. This means in Dec i will have to do drop box and there is no way my wife can get her h4 stamp before Jan to travel with me.
Any thoughts on how to solve this…