I use Memoria Press Prima Latina starting at around 7, whenever they read English fluently. I am using it with my oldest grandson now.
It has pronunciation CDs but I don't use them. I don't like their accent.
I find it really helps to have the children learn their basic prayers in Latin. They can memorize them without a detailed understanding. Then, as we learn grammar and vocabulary, we go back over the prayers and see how it fits. Memoria Press is a Christian (though not explicitly Catholic) publisher so they introduce a lot of the prayer vocabulary.
This is the same thing that Cantarella linked to.