Catha edulis is notorious for being a species with low germination rates after a few months of the seed coming off the tree. I was able to obtain very fresh seeds. I laid the seeds on the top of the soil, not covered. They sprouted after a week or too. The plant is currently moving onto it's third set of leaves as of writing this post.
I wish you the very best in growing it =)
Someone gave me a seedling tree a year or so ago ago and I have it in a bucket in my garden. Where in the world are you growing this?
I am growing it in Australia. Your plant looks healthy. Have you tried it before?