It varies by state, with about half having waiting periods between 3 and 10 days. Almost all of the rest do allow revocation of consent to be ordered by a court, but those usually require a reason like it was under duress or fraudulent in some way.

Almost all states, though, have a "no-sign" waiting period of a couple of days between starting the process and finalizing the concent to adopt. I wonder what happened to that..