Thanks! I appreciate the response. As far as my goals, I think I am probably in camp 2 from what you described, Ester Maria. It may change to camp 3 depending on our future. But, for right now, camp 2. He is the oldest. Although he is a very quick learner, I would rather wait until later so I can include some of my younger kids in the study.
The other thing is that sometime in the next 2-5 years we plan to move overseas for a very long length of time, somewhat permanently. However, we haven't decided absolutely where yet, so I am not sure what kind of modern language to start at this age.
I guess one of my concerns is that my children would be confused/frustrated by learning a new modern language at the same time as beginning Latin. Moving, especially to a new country/culture/language, is a hard adjustment and I don't want to throw too much at them at once. But, I see you advise that even 5th is not too late to start, so that really does give me a broader window of time than I thought. Thanks! :)