Ooh, nice selection 😄. I already had all of those saved, though I usually wait for images to get to Pixiv before uploading.
At the end of the day it's your choice whether to wait for the Pixiv version or not, of course, but a lot of the time fanart posted to Twitter never makes it to Pixiv, or sometimes the artist intentionally posts a lower res version there, and if the artist posts a bunch of their recent art all at once as a log then the original commentary won't be preserved.