Hi, I started Humphrey on raw when he was about 7 months. I read quite a lot of conflicting advice as to the best way of doing it but decided, as he was young, to go cold turkey so literally just abandoned the kibble and went straight onto to raw.
I can't get any ready made mixes here unfortunately, so have to DIY it, which is a lot more work but at least does allow me to determine more easily what he likes or doesn't. He always spat liver out for example but I found if I cut it up really small and mixed it with tripe (the mega favourite!), he'd eat it. It can often be the textures they don't like as much as the taste. He was a bit reticent at first but as soon as he realized he wasn't getting anything else, he ate it and now he loves it.
If it was me, I'd say try and stick it out, maybe experiment with different mixes or add something you know he really likes. There are so many benefits to raw, it really is worth giving it a good go before you give up and change, or you could try it again in a few months but I tend to think the younger tney are, the more adaptable they are . Best of luck, hope you can get it sorted!