I made a mistake and printed tickets to the museum for the wrong day of our visit to DC in October. By the time I realized my mistake the time on the correct day was filled. Is there a way to still visit one week sooner?

Nope

You might also chance going early to opening. I visited without ticket in late fall, i.e., not during summer vacationer's travel season, and in line there were quite a few people with extra tkts who gave them away.

Yes starting September no tickets are needed

Or Monday- Friday at 1pm they let walk ups cone in

I dont think so, try to get tickets the same day you want to go at 630am et

@ 1pm, they give away tickets (during the week)