when to tell work or apply for FMLA?

I think you'll also find that your care team will work with you to make any appointments you need as easy as possible on you and your family in terms of you being the sole support.

I told my boss about my situation after I knew I'd need chemo. He allowed me to reduce some of my work responsibilities and to work at home. I was at the office two days a week, and kept up my usual teaching load (two classes). I got my surgery (lumpectomy, no reconstruction) done during Christmas break and did radiation during spring semester after I'd finished my teaching for the day. So, it's possible to work through treatment. I should add that I was 47 during treatment and had no other major health problems (except high blood pressure, controlled by meds). Not everyone can work through treatment, though. I'd wait until you had a treatment plan in place, and you have an idea of what you'll need to get done.

I filed for FMLA once my diagnosis was confirmed. I worked thru my chemo for the most part. I had chemo on Fridays and took that day and the following Monday off for a rest day. Those were considered FMLA days - unpaid day off. Once I had my surgery I went on short term disability. I was off for 4 months and received 60% of my salary during that time. I could have come back somewhere in the middle, after my mastectomies but before my exchange surgery. And then went off again after I had my exchange surgery. But my employer told me to just stay off. They said they wanted me to come back, but not until I was healthy enough to do so. My employer has been SO good to me and has worked amazingly well with me during my treatments and surgeries.