I've done both and I personally prefer beginning of day. Standups are usually (in my experience) the beginning of a conversation or a brainstorm and that works

I've done both and I personally prefer beginning of day. Standups are usually (in my experience) the beginning of a conversation or a brainstorm and that works better when there is time left to continue after standup. If they are just reporting what you did then end of day might be better, but that sounds like a bad standup.