Ok, so I figure most of us are around LT and LTCmdr, meaning most are close to SOL. I did a quick check and saw something like 35 instances in Regulas, all around 15 people. I imagine it's close to the same for Sirius et. all. Figuring a majority in the 4 neighbors Sirius sector blocks, That means there are around 2,000 people in the "warp" sectors alone.
I'm guessing there are more people in mission instances than world instances. Based on my play time of about 10 minutes missioning for each minute of "warping."
Roughly, I figure about 200,000 people playing (or Trying to Play) right now. No wonder there are queues, as based on what I goggled that is about average for a seasoned MMO.
I don't know if that's a good thing or a bad thing, I just know that I can't help myself.
Judging from various current queue numbers, I would estimate current players at around 5,000 at most. It is after all only Pre-orders at this point. Cryptic needs to work really fast because there will be 15,000+ people at Launch and they aren't going to sit patiently in a queue after installing STO for the first time