Why would Cindy have good reason to remember March 2008? Actually she said today on the stand that she had NO good reason to remember March 2008 because nothing was happening then - Caylee was alive and times were normal.
Also her supervisor would have access to work records. Timecards, days off, vacation days, emails sent (even if Cindy's email account was deleted as she insisted, the coworkers and supervisor's email accounts are presumably still functioning and might have records of emails sent by Cindy) - perhaps doing a date search any number of people will have records of Cindy saying she'd be late to the meeting, or that she'd made brownies and they're in the front office, or a work or personal email of any kind at all.
Her cell phone pings will hang her...