At what point in history did the Spanish and French languages drop their noun declensions?

Vulgar Latin developed differently in the various provinces of the Roman Empire, gradually giving rise to the different Romance languages. József Herman states:

It seems certain that in the sixth century, and quite likely into the early parts of the seventh century, people in the main Romanized areas could still largely understand the biblical and liturgical texts and the commentaries (of greater or lesser simplicity) that formed part of the rites and of religious practice, and that even later, throughout the seventh century, saints' lives written in Latin could be read aloud to the congregations with an expectation that they would be understood. We can also deduce however, that in Gaul, from the central part of the eighth century onwards, many people, including several of the clerics, were not able to understand even the most straightforward religious texts.[8]

As early as 722, in a face to face meeting between Pope Gregory II, born and raised in Rome, and Saint Boniface, an Anglo-Saxon, Boniface complained that he found Pope Gregory's Latin speech difficult to understand, a clear sign of the transformation of Vulgar Latin in two regions of western Europe.[9]

At the third Council of Tours in 813, priests were ordered to preach in the vernacular language – either in the rustica lingua romanica (Vulgar Latin), or in the Germanic vernaculars – since the common people could no longer understand formal Latin. Within a generation, the Oaths of Strasbourg (842), a treaty between Charlemagne's grandsons Charles the Bald and Louis the German, was proffered and recorded in a language that was already distinct from Latin.

READ MORE http://en.wikipedia.org/wiki/Vulgar_Latin#The_loss...

As for Phonological changes

http://en.wikipedia.org/wiki/History_of_French

http://en.wikipedia.org/wiki/History_of_Spanish