You cannot apply for naturalisation unless you have no time restriction on your stay in the UK; that is PR or ILR.
As you entered the UK under the EEA rules you have to continue under those rules and cannot switch to the UK immigration rules, so you cannot apply for ILR but have to apply for PR, which you cannot do until you have lived in the UK for 5 years. Although as you do come under the EEA rules, you don't actually need to apply as you will receive it anyway. But I would recommend doing so as it can save complications when/if you need to demonstrate your right to live in the UK.
Normally, once someone has held held PR for 1 year they can, provided you meet all the other requirements, apply for naturalisation. However, as you are the spouse of a British citizen you should not have to wait this additional year
see
https://www.gov.uk/government/publicati ... en-form-an for more details of the requirements for naturalisation and how to apply.
The official advice is to allow up to 6 months for an application to be processed, but usually it is about half that.