As soon as she gets ILR, she can apply for citizenship as spouse of BC provided she meets the 3 year residence and other standard requirements, Life in the UK and English level B1
The UKBA link below gives the detail you need :
http://www.ukba.homeoffice.gov.uk/briti ... ofcitizen/
Residential requirements
In order to demonstrate the residential requirements for naturalisation you need to:
have been resident in the United Kingdom for at least three years (this is known as the residential qualifying period); and
have been present in the United Kingdom three years before the date of your application; and
have not spent more than 270 days outside the United Kingdom during the three-year period; and
have not spent more than 90 days outside the United Kingdom in the last 12 months of the three-year period; and
have not been in breach of the immigration rules at any stage during the three-year period.
And the FAQs, link below also :
http://www.immigrationboards.com/britis ... 95747.html
Eligibility
Q1: I was just granted ILR, when can I apply?
If not married to BC, the standard requirements need to be met. This includes holding ILR/PR for at least 12 months before applying.
If married to a BC, you can apply the same day you are granted ILR if you meet the spouse requirements which includes 3 years residence. Any legal stay in the UK counts.
An important requirement you should pay attention to is that you need to have been physically present in the UK at the beginning of the 3/5 years residence period i.e. the day the HO receives your application 3/5 years back. This is a pass/fail test and the HO has no discretion with this requirement.
