Getting the hour wrong is completely excusable. I have managed to get the day wrong in two consecutive weeks.
Last week, nipped to local shop, just as I was approaching it, I thought "Heck, it's Weds it's closed on a Wed afternoon". Came home. Moaned at Mr BM about possibly having to go to Tescos cos the shop is shut on a Weds afternoon. "It's Thursday", he replied.
This week, said to Mr BM "Just nipping to the shop." He asked "Is it open" to which I replied yes it is. He said "But it is Wednesday". In my head it was Thursday.
Clearly, I am working too hard. And thankfully today IS Friday (so I have been reliably informed).