So sorry to hear that you have been recommended for an interview. This separation from our other half for months is hell indeed and an interview on top of it can make anyone turn into a bundle of nerves. But take it as positive where you can show NDVO face to face that you two deserve to be together and you marriage is genuine. Are you the sponsor or the applicant? You can really show NDVO that your 11 year old daughter needs both her parents in her upbringing to ensure her well being and you are dedicated to each other.
As per NDVO's general trend, applicants find out date of interview approximately one month after they find out that interview is recommended. So you might get your dates in March and interview held in April.
I think too that your wife should get the medical treatment she needs so that she can have a better quality of life. If her family or close friends can look after your daughter in that time, it would be ideal. She should not delay in case her health could become a little worse.
I hope that everything works out for the three of you.