Does my HTML5 doctype have to be on the VERY first line?

Question

I\'ve always wondered whether whitespace before a DOCTYPE matters, but I can\'t seem to find any definitive information on the web. People say not to do it,

Answer 1

Actually, the practical advice is to limit initial text that includes a statement to 1024 bytes. This is due to the need of some browsers to use a limited prescan to determine the character encoding quickly if a character encoding header is missing.

See W3C and Sivonen for details.