I've set up a SFTP server and the group "sftponly" and they are all chrooted to the same dir. I'd like to give one of those user exclusive access to a specific folder for a short time. Can that be done without changing too much? Maybe with a match option in the sshd_config?
That has nothing to do with
sftp. You just want specific permissions set on the desired directory. You can use
at to queue a wait action, eg. to chagne the permissions again after some time.