R' Josh Backon wrote:
> The entire "oylam" requires a waiting period
> of 24 hours (after cleaning) for Libun Kal.

Rav Shimon Eider (Halachos of Pesach, 2-volume edition, pg 159) 
writes:

"Kashering with libun (whether libun kal or libun gamur) may be 
performed even immediately after use. There is no requirement to wait 
24 hours from the time last used."

His sources are: "Darkei Moshe Yoreh Deah 121:15 and Aruch Hashulchan 
ibid:22 and elsewhere." (Disclaimer: I did not look up those sources 
personally.)

Akiva Miller