I'm presuming this is a 15 inch. I'd sell it NOW. I personally think there's no better time to sell used Macs than the week *before* the MacWorld Expo. You'll never get a better price.
I used to think leaving the RAM in made for a higher sale, but now I'm not convinced. I recently sold my 1.8 MacBook, and I removed the 2gigs I'd put in it, and replaced it with the 2 256 chips. Sold for top dollar ($975). I then used the 2 gigs in the new Black MacBook I got.
Then again, if you can't use the RAM in a new machine, you may be better off selling with it in it.
M1 2020 Mac mini (16G 2T) • Ventura 13.x • Dual 27" Dell S2722QC monitors • M2 2022 13" MBAir (512G 16G) •