Stella-Maria,
Sorry for responding late - in fact, I was in doubt so wanted to make sure before I reply.
I was WRONG in my previous post to mention that you are not NIW. I realized that Schedule A is part of NIW category. Your approval notice says SEC. 203(b)(2) - and that's for exceptional ability/advanced degree - I am not 100% sure whether the approval was really under Schedule A, because chemists are not listed as far as I could recollect. If I get time, I will try to find out list of Schedule A professionals to see if chemists are listed there. Meanwhile I recommend to do "google search" with "NIW" and "Schedule A" key words - also make sure that you visit the US department of labor web-site. If I come across any information that might be useful to you, I will respond ASAP.
Anyway, this means that your category is NIW (and most probably Schedule A - because they approved after RFE to that effect). Since you have a sponsor, you should be working for your sponsor (if not, see if AC21 is applicable) at the time of interview. They might ask you to show recent employment letter with description of your duties, evidence for eligibility to Schedule A (similar to those submitted during I-140), recent pay-stubs, and other routine documents (like I-94, etc.).
The interview letter will describe what documents to be carried with.
Again, I would like to highlight that this is my non-legal point of view only - I have no experience in this regard. In fact, my case is also an NIW case - self-petitioned, no sponsor (and not schedule A) and judging from the recent trend, I expect local transfer to NY (my God!).
Best wishes,
Jigesh