How long after my return is accepted will the amend option show up (missed a 1099-MISC)?

The option to amend should be available right after your return gets accepted. If you filed a state return, then please wait until all of the returns have been accepted.

https://ttlc.intuit.com/replies/7276596

Perhaps it won't show up until my state returns are accepted as well? It's a self-employed return. Does that matter?

Yes, all of the returns have to be accepted