Well, there isn't really a clear-cut answer to this question as the definition of "price" and "exchange rate" can be interpreted differently depending on the context. In general, however, exchange rate usually refers to the value of one currency against another while price refers to the amount of money required for purchasing goods or services.

As for when we should start using "exchange rate" instead of "price", it really depends on what you're referring to specifically and how people within a certain community decide to adopt new terminologies over time. Meme-ing has certainly been a powerful force in shaping popular culture and language usage throughout history, so it's possible that new terminologies could be coined through humor or internet memes as well!