Where did the original phrase third time is a charm originate from?

The first time we come across what appears to be a precursor to this phrase is in Elizabeth Barrett Browning's Letters addressed to R. H. Horne, 1839:

'The luck of the third adventure' is proverbial.

It is listed explicitly in Alexander Hislop's The proverbs of Scotland, 1862:

"The third time's lucky. "