Hi, sorry for wading into this late (have been busy at work). I’ve taught young kids and think it really comes down to your own ability and confidence in Latin.
If you’re not comfortable with Latin yourself, the course will need to do all the work and so starting with e.g. Hands Up Education’s Primary Latin could be a good approach (it’s designed for use without a teacher in mind):
https://hands-up-education.org/primarylatin.html
The course after this in the series is Suburani, which would be too mature (in themes) for young kids: slaves getting tortured etc. You’d need to move to something else.
Also, kids respond well to gamified learning (Quintilian talks about this, giving kids ivory letters to encourage them with spelling) and so e.g. Duolingo’s Latin course is not very idiomatic but could be a useful add-on, if it gets the kid engaged (that’s the main thing you want at this age I think).
If you are more comfortable with Latin, you can mix it up with different materials and supplement with conversation at home, adapting the materials (the start of Cambridge Latin Course seems optimised for this usage: kids can easily make up sentences to describe what’s going on in different rooms at home after a chapter or two).
I also found it helpful to engage kids by creating videos using a movie-making app that came on the computer. You can supplement this with some Roman history (I’ve taken lots of videos of Roman history online and edited out the gruesome bits using the movie-making app).
What I’ve found is that the method you expect will be best turns out to be boring for them, and what you least expect will work well sometimes resonates. I was surprised when young kids responded better to e.g. Peter Jones’ Learn Latin (which gets into the old-fashioned grammar grunt-work) than reading-based courses full of pictures.
It really depends and you need to try out methods until you find the ones that work (for a bit at least, before you reset and try something else!). Also think about what you want the kids to get out of it. If you’re looking to pre-load as much morphology into their young receptive brains as possible, you may find that they end up dropping out later (most kids do); it’s the one who get enthusiastic who continue and succeed, and so that’s what you should look to nurture at this age in my view.
Cheers, Chad