When was the Declaration of Independence signed into effect?

If one means the formal pronouncement by the Continental Congress that the colonies are independent, then it is July 2, 1776, when a voice vote was taken on declaring independence. If one means the document itself, then it would be July 4, 1776, when the written document was approved by all delegates and John Hancock and Charles Thomson signed it to authenticate it as a pronouncement of the Congress so it could be printed and distributed to the states and armies. The copy with the 56 signers names did nothing to alter or confirm either the July 2 vote or the July 4 adoption of the document.