The Start time is based on the Mail Source Agent Server Time. As some components used with Migration Manager can be remote, there may be several time zones in play for a migration session. To ensure the correct time-frame is chosen when using the Auto Switch feature, base the desired start time on the Mail Source Agent host time.
This can be verified in the Mail Source Agent Log by searching for the following log line:
12/3/2015 6:08:31 AM MailKernel::IsReadyToSwitch Informational 2090 Synchronization status: Item cannot be switched before the switch date '12/3/2015 6:10:00 AM' set for collection 'Collection Name'.
This log can be found on the Mail Source Agent Host in the following location:
Mail Source Agent
EMWMSA.log and EMWLibs.log
%SystemRoot%\system32\Aelita Exchange Migration Wizard\Mail Source Agent\