Hi TKS, You probably have some more information by now but your doctors should be able to answer your questions about delays, treatment and reconstruction. I can only give you my experience. I was diagnosed with ILC on 5 December after a routine screening mammogram. According to my surgeon, it was amazing that it was picked up. I had CT scans to determine whether there was anything elsewhere and the tests say not. My tumour was assumed to be approx. 2.5cm with no node involvement and the biopsy showed that it was not particularly aggressive (Ki67 <10%). I told the surgeon that I had some events at the end of the school year that I really wanted to go to and he was okay with that so I was scheduled in for a partial and sentinel node biopsy on 21 December to get in before Christmas. Unfortunately, the path report from that came back with a tumour size of 4.5cm, no clear margins and 3 nodes involved. I had a full mastectomy (I'm not that well-endowed, either) and axillary dissection on 8 January. I always knew that radiation would be on the cards but the size and node involvement meant that I would need chemo. I have had 4 AC treatments and this morning I had No 7 of 12 Paclitaxol. Rads will be next and then hormone therapy. My surgeon (who is quite well-known and respected for his work) said that he would not consider reconstruction for at least 12 months. Whether I go down that path, I don't know as yet.
ILC is a nasty beast as it hides so well. My guess is that unless your cancer is aggressive, you will probably get the okay to delay a couple of weeks but that is only a guess as it will depend on your individual diagnosis. In the end, your twins will want you around more than they want a cruise. I should mention that a relative was diagnosed with ILC a couple of weeks after me. Due to Christmas and the public system, she didn't have her first surgery until April, so as you can see, everyone can be different.
Good luck with your appointments and decision making and let us know how you're going. We all remember how overwhelming the first few weeks are.