I ordered some 2023 forms last year just in case IRIS crapped out.  It did.  But I managed to get everything filed before that happened (well, hopefully, folks are now saying they can't access their data at all so maybe everything was lost in a server crash).

If you're ordering now, might as well throw in some 2024 forms.  They don't always ship right away but then later in the year I get a surprise package.  "Oh yeah, I forgot I ordered those things . . . "

https://www.irs.gov/forms-pubs/order-products