Recently diagnosed

Hi there,
I am 36 with two young kids currently living in New Zealand. We were planning on moving back to Ireland when I found a lump last month and was diagnosed initally with Grade 2 triple negative but changed to grade 3 ER positive after my mastectomy last week. I had 1 lymph node involved but also has drained to Internal mammary nodes which they could not remove so I will definitely be having chemo and radiation. Flying home next week to get my treatment started but not sure what to expect next. Have had MRI prior to surgery and had CT yesterday. What other tests did you do before they decided what kind/length of chemo you were having? I am anxious about delays in starting treatment. Any advice would be much appreciated x