What was the first spanish-speaking country?

The root of the word is literally "Spain", although there has been some debate about it, it is in fact Spain.

The official Spanish speaking countries are: Spain, Colombia, Perú, Venezuela, Ecuador, Guatemala, Cuba, Bolivia, Honduras, Paraguay, El Salvador, Costa Rica, Panamá, Equatorial Guinea and Puerto Rico. but Spain was the first actual country to begin speaking Spanish. 

The answer is they