Indeed.
But, for those who did not discover third-party tools, before the journals, you might have problems. I've submitted requests for my First Discovereds from before I started journal logging, and I might as well be asking for today's' SIOP's and PAL links...
Well... here's the weird thing. I just recently learned about EDDiscovery. I've been using EDMC mostly, but decided to install EDD (maybe 3 weeks ago?).
After it starts, it does some kind of syncing. And now, the first entry in EDD is from 10/25/2016 8:58 AM, with the log saying "Fileheader | Version: 2.2"
Basically, it seems like ED added a log in 2.2 that is permanent on your computer (or at FD through the API?), so even if you install it now, perhaps it can pick up the old data as it did for me.
I does however look like there's data missing between Nov last year until May this year on the computer, and I think it's because I played on a different computer during that time, so the log seems to be local to your harddisk in this case. But it does show exploration data from last year (even though I just installed the program 3 weeks ago).
Try it, but do it on the computer you've been using, and see if it works. If you're on PS4 or XBox... well... then...
But with that said, I always wanted a feature that you're suggesting anyway. To select the systems that I discovered first. Would be nice.
--edit
Just confirmed, the log file is localized on your PC. And it starts from 2.2 version.