Mari Gilbert filed a missing persons report a few days after Shannan went missing. So...sometime around May 4th, 2010.
Melissa Barthelemy's family tried to file a missing persons report 24 hours after Melissa's disappearance on July 9, 2009. They were brushed off by NYPD. They had to appeal to the Erie County Sheriff to pressure NYPD to take the case seriously and file a report. This took a couple of days.
Megan Waterman's family filed a missing persons report the day following Megan's disappearance on June 6, 2010.
Maureen Brainard Barnes brother and sister tried to file a missing persons report for Maureen immediately after her disappeance on July 9, 2007. Police brushed them off. Not sure when an actual missing persons report was filed for Maureen, but I do know that Missy stayed on LE until they did file one...so probably within a week of her disappearance.
Amber Lynn Costello was last seen on Sept.2, 2010. A missing persons report was never filed.