Nothing special. I just mentioned to the person collecting the documents that my wife wanted to travel later, although I had mentioned in the DS230 that we would travel together. He replied that they issue separate packets in any case and that my wife will be able to travel later as long as she travels within 6 months of the interview date.
So just mention to them that you guys want to travel separately and when you collect the IV packets, make sure that for your spouse it is mentioned -- valid for travel with primary or follow to join (I forget the exact wording).