One odd little fact about the English that goes all the way back to pagan times is that we (like others) reckoned the beginning of a given day to be the evening rather than the morning

So if it was Tiw's Day, at sunset it would become Woden's Eve

Sunset on Woden's Day would begin Thunor's Eve

Tacitus writing about the Germanic peoples in general: 'Instead of reckoning by days as we do, they reckon by nights'

For a stark reminder of this: what's the term we still use in England for a period of two weeks?

Midsummer's Night, as in the Dream, was actually Midsummer Eve - the night *before* Midsummer

Consider also: All Hallow's Eve, St John's Eve, Christmas Eve, and so on

All this because the 'eve' wasn't a separate event to the day, but going by the old rule, it was the first part of the day itself