If you want to file another Chapter 7, then you must wait 8 years from the date that the previous Chapter 7 was filed. Bankr. Code 727(a)(8).
If you want to file a Chapter 13, then you must wait 4 years from the date that the previous Chapter 7 was filed. Bankr. Code 1328(f)(1).
Based on your question, you could file a Chapter 13 now, but a Chapter 7 would have to wait until the year 2017.
As far as only one of you filing bankruptcy is concerned, it's legal, but usually not the best plan. I would have to know everything about your financial circumstances, before I could provide a competent answer concerning individual vs. joint bankruptcy. That's not practical to do in this forum -- you would be better to consult with a local bankruptcy lawyer, in a confidential setting.
I hope I've answered your question. Please let me know if you require further clarification. And, please provide a positive feedback rating for my answer -- otherwise, I receive nothing for my efforts in your behalf.
Thanks again for using Justanswer!