Just came across this original document, that may explain why in some documents 00:01 hours was mentioned and in some 01:00 hours. It was a message from Dönitz to the Wehrmacht commanders on 7 May 1945 and stated "...by May 9, 1945 at 0000 hours, all active combat is to cease, no vessel, aircraft of any kind to be destroyed or damaged, and after 0100 hours all German Forces to obey commands from Allied and Supreme Soviet Commanders, or punishments will be exacted by those forces on Germany."
Source:
https://www.bonhams.com/auctions/24254/lot/1239/