Start by reading the
Standard requirements for naturalisation (click). You will note that:
Immigration time restrictions
You must be free from immigration time restrictions on the day you make your application. This often means having already gained settled status before you make your citizenship application. How and when you are eligible for settled status will depend on the immigration category you were in and successfully meeting its requirements for indefinite leave to enter or remain. For example spouses and civil partners of British citizens who must complete a 5 year probationary period under Appendix FM would generally have the opportunity to apply for naturalisation on this basis once they complete the 5 year period and obtain indefinite leave to remain provided they can also meet the other requirements of naturalisation at that time.
Thus you must be settled, in your spouse's case, have ILR.
The fact that she is married to a British citizen, just means that she may not have to wait 12 months after having been granted ILR.