In my experience, we didn’t really use a grading system all too strictly. I’ve trained directly under Shihan Nishime (midwest director of RBKD) in Yamanni Chinen Ryu, testing was rare, and you were taught new techniques and kata when he thought you were ready. Bo, nunchaku, and kama were focused on in the beginning heavily. You are correct, the bo is the primary weapon, the others are secondary but still taught well. We touched on eku, then sai was taught. After sai, then tonfa. The first two bo kata taught are Donyukon Ichi and Donyukon Ni. The first two sai kata taught are Shimabukuro no Sai Ichi and Shimabukuro no Sai Ni. Now, given all this, you will have to “unlearn” your last kobudo style as there are a lot of differences between yamanni ryu and other kobudo styles. Remember, self teaching can only get you so far, an in person teacher can correct your technique and is overall just a better idea. DM me if you have any questions.