Do you mean British Citizenship?
Just looking at the Gov.UK website it seems (maybe just me) a bit confusing.
You can apply if the spouse of a British Citizen after 3 years!!!! (I thought it used to be 5) but then it says you must also have ILR!!!!
If you have ILR this says that you must wait 12 months after obtaining it!!!! (This did not use to be the case, as long as you had been here 5 years then you could apply, Nok applied straight after getting her ILR).
There are also some qualifying times that you need to adhere to:
You should also not have:
spent more than 450 days outside the UK during those 5 years
spent more than 90 days outside the UK in the last 12 months
broken any UK immigration laws (for example living illegally in the UK)
Have a look here and see what you think, others might comment as well.