How to set wait time for picking files in SFTP server or wait time in message mapping

Hi,

I have an inbound scenario, where around 50 files are getting processed in PI and sent to ECC at a time. I want to have a wait time either for picking the file in SFTP server (like, 1st file and 2nd file picking time difference should be about 30secsand so on)

or

we can have wait time in message mapping.

Let me know how we can configure that