Let many other including myself, your wife has very limited options. If she leave US, she can not enter US after filing the I-130. If she plan to stay, she will need to do what she can to be legally here. Hope she can get H1 after her OPT. Else, back to F1 or other legal status.
Not everyone is that lucky. If she can not maintain her legal status, she can return home and stay there until your I-130 is approach and her visa number is current to file at home country.
In general, I-130 takes 5 years and up. So, it is a long painful process. I have experienced it first hand. We run out of all options. but we are at the end of the journey now. My suggestion to you is to file for USC as soon as you can. Once you are USC, things will go along faster. About 1 year to get her GC. If she happen to fall out of status (e.g., overstay) during this period, she can still get her GC after you gained your USC.
The spouse of LPR is in for a hard life unless he/she is in H1-B or F1 or some other visa.
There is also something call K-3 visa. But I did not explore at that time, don't remember why. It is kind of new, do read up and see if it does you any good.
Good luck.