As far as we know.... Apple announced that the Ipad 3rd Gen is going on sale 16 Mar.... they didnt specify a time like they did for the iPad 2
I'm pretty sure Apple didn't specify the time for the iPad2 until Thursday before launch.
http://www.macrumors.net/2011/03/10...-100-am-pacific-online-500-pm-local-in-store/