Yes, you can if she can stay in US or where she is legally
I was under a simillar situation, but my wife was on a dependent Visa and because of that she couldn\'t stay in US. For this reason I had to go for the interview with my wife. But if your wife can stay legally in the US ( if she is in US) after you get your CP done, then yes you can ask for a later date for your wife, and you need to mention that on the packet III or call that in advance before they schedule your appointment date.