First I looked it up and got to the 1 year anniversary post.
I flagged the image to see what time it was posted. May 17, 2021. This tells us the first meme was posted sometime around then.
I proceeded to search "imgflip ms_memer_group may 2020" and got nothing of note. However, I did find Spire has a Twitter account, and it seems back in the day she tweeted a lot of memes from MSMG. So i went back, way way back, and the first one on this board was from May 19, 2020. That was the image posted, it says, "First meme post"
This is probably the closest we're going to get.
Caption this Meme
