I think they call such things memes here, and if it is indeed a meme, then it is the first one I've ever done as well. Feel free to adjust it or add things to it to accommodate your own journals (and perhaps I'll copy some of those changes from you as well).
1. My first entry here was on 1 February 2016, here it is:
2. I posted 78 entries in my first month on LJ (that's some seriously hyper LJing and I don't think I am much slower now)
3. In my first month here 343 people visited my journal (256 of them were fellow LJ users), 32 people friended me, 2 people unfriended me and 31 person left 421 comment in my journal
4. I received my first comment here on my 5th entry and on my 3rd day here
5. My first commenter was lutik_sun
6. My first commenter I am still friends with was wosny, it was my 6th entry on my 3rd day here
7. My first friend friended me on my 6th day here, it was davesmusictank
8. The first friend to friend me who I am still a mutual friend with was randomdreams who friended me on my 7th day here
9. The first friend unfriended me on my 22nd day here, it was serjiojitser
10. The first like I received was from prorsus
11. My first subscriber was jilted84
My favourite entry in my first month here was this one:
Q: Do you think this journal was more interesting in its first month or it is now?
A: Definitely in its first month.