We are filing married jointly for the first time, but it has not asked my wifes income. Where do i enter this information?

When you are entering income on a joint return, every income entry screen will either have a spot with both spouse’s names there, or when you click to enter a W-2, 1099R, etc. it will ask you by name which spouse it is for.  You do not have to wait for the software to “ask” you for your spouse’s income.

Make sure of your filling status in My Info.

To check your Filling Status.  Follow the steps bellow.

To confirm your Filling Status

1. Select My Info or Personal Info
2. Click the down arrow next to your name
3. You can see your filling status here.
4. If you need to change it:
5. Choose [Revisit]
6. Continue the interview to About your household
7. Select Married filing jointly

Xmasbaby0 accurately described the resulting affect. 

I had a situation like this for my son.  His new wife is here legally but not yet officially a citizen.  There's a grace period for people in this situation of a year I think.  If she has a SS# but no tax withholding from her job or if she doesn't have a job, or if she earned her income in another county, I don't believe you need to include her income.  So say you've applied for her green card and she's here on a spouse visa.  Just file it normally and then next year when she becomes a citizen you will include her income and W2 if she gets one. TurboTax will ask you the questions regarding her status. - If this is your situation. - Best if you research this yourself but this was the way I handled it.  There is some supporting information about this online but it's not super clear.  Make sure to file jointly but you seem to be doing that.