Again thank you very much jackolantern.
The appointment was the most pleasant government office visit I have ever had. I walked in, filled out a form and immediately saw someone who checked my GC + Appt letter + form I just filled out (the form has nothing you didn't already fill out: name address etc.).
Then they directed me to desk where the officer(? - was dressed casually) looked at my GC, and in fact got the sticker ready the minute I gave her my paperwork. But she did some computer entries and also signed a log sheet and she took about 5 minutes while I was sitting there studying the visas on my passport (don't try using a cell phone, even for internet etc. - I knew better than to try). She put the sticker on and then said it will come in the mail in 5 months.
Then I went to get FP'd and she looked at the photo on the computer screen and my face, then scanned the appt. letter and called me for the fingerprints. Wow they take every single finger and they take them good. Left and right sides of every finger, retakes for quality control, they are not playing around with that part of the process. Then I sat for the photo, and finally I was told I could go.
In all in was maybe 15 minutes with no wait anywhere. Somebody tried to take their appt. early and they turned him down and told him to wait for the appt. date, he was the only person in front of me in line. (Varick St. NYC - for everyone's information). I think they tried to help him by telling him to try asking at another office, but I don't know what finally happened. They were not busy at all.
All in all no issues (that I am aware of), no problems, no hassles.