I am also in the black, looking for first discoveries to add to my growing list, have no where near the numbers you posted, at least, not on this second account. Have just over 3 weeks game time on this second account and have amassed over 10k first discoveries so far. Bought the account solely for exploring, and didn't think it all the way thru when I 'named' the account. So before I made my first "first" discovery with the account, I petitioned f-dev to change the name of the commander to the same as my first account, albeit, a slight change in the letters, like using 2 "V's" for the second W, that way, all the first discoveries made will sport the same name, or at least it will look the same at first glance. There are a couple hundred systems out there that I had partially scanned on the first account, and went back thru a year later on the second account and finished scanning the whole system, so they have two different spellings on the discovered by, but the same name.
Currently on my first trip to Beagle, but ain't making much headway initially, in 2 weeks since I started am only 14k lys from the bubble, been scanning all the nebulas I come across and it takes time to find 'firsts' in the Nebula regions, so spend a few days til I find several systems that are undiscovered and then move on to the next one. I'll eventually get there though, I aint in a hurry. Gotta swing by Colonia region first to sell what data I've collected so far and update my spread sheet with all the first discoveries so far, with this batch I haven't turned in yet will put me over the 50k mark, still gotta bunch to find to reach the Mil mark though.
