Hi there, while there's always more to be said on this topic, you may be interested in this section of our FAQ about musical scales and tuning.

well....it wasn't!

Here are some notation styles from the 18th century (since your question states that it was standardized within the 17th century I'll show you some examples post-17th century to prove that it wasn't) :

Couperin, 1714 (French "white" notation): http://i.imgur.com/uVk1awC.png

Bach, ca. 1730: http://i.imgur.com/jOJkdEe.jpg

copied in England, 1704: http://i.imgur.com/BvBK1qz.png