From what I know from various activities (going through the official websites, talking to people who were already admitted to some program, and so on.) I can say for sure that if the deadline of a particular school is in December or January. It takes at least these two months (Dec and Jan) just to sort out the application, match the official score reports, unofficial/official transcripts and other stuff to our application. The admission committee meets itself for the first time and sees any of the application for the first time in January end or February starting at the earliest.
Some of the posts in Gradcafe or elsewhere might be genuine, but from my experience I have seen people bluffing about stuff, just to get additional online attention. Thus it would be better to wait for official confirmations from the schools and not panic because someone posted that they got an interview invite from a particular school, or they heard that they got someone else getting an interview. For all, I know that unless I hear from the school itself that they are interviewing folks, I am not going to believe it. I have seen people creating false GMAT scorecards and sharing online, just for getting a kick. Then just writing about interviews is not a big deal. I am not saying that everyone or majority of us lies, but such bluffing is not an uncommon phenomenon.
Also, some initial interviews are even to clear somethings up. If our profile is unambiguous (either good or bad), then they might not think it to be urgent to ring us up. However, if our profile has some red herrings, then they would like to clear them up, such as a gap in education or work experience unaccounted for in the application.
All these are just my views on the application process, I might be wrong, but I am done with the panic creation by writing that ABC or XYZ got an interview for DEF college, so we are out and so on. Although this is a sweat thread, we can help each other out for supporting each other, irrespective of whether we are a domestic or an international applicant, by boosting moral of each other and sharing stuff from past trends from official sources.
No need to look even beyond this website, just check the 2016 Ph.D. sweat thread here itself, initially people were just as panicky as we are, but then they were getting interviews and admitted even after the April 15 deadline, and this is not uncommon for any Ph.D. to say.
Apologies for such a long and emotionally intense post, but I am new to this portal, and I thought like to share this. I might be wrong, but this is what I feel, and I shared it with you, as we all are going through the same turmoil.