When I first started training in 1976, weapons training did not occur until sometime after Sankyu. As it was explained to me at that time, this was because it took the Aikidoka at least two years to get the basic body movements down well enough to begin to appreciate weapons training.
Presently, I start students with bokken training prior to their rokkyu examination, and their jo training prior to their gokkyu examination. My reasoning is that they will need all the time they can get to adequately train their ability to handle the bokken and jo so as to do a credible job in shodan.
As a consequence, my students have the basics fairly well in hand by the time they are preparing for shodan. This allows them to focus on ki development, flow, technical precision and all those other intrinsic qualities needed to do somehting more than "cookie cutter" ken and jo gi.
My only problem with "weapons training" is the term "weapons training". Yes I know the bokken and jo are weapons, however, from my perspective within Aikido, and attempting to follow the principle of katsujinken in my training, I have difficulty with the term.
We seem to be stuck with it for now, and I do take time in class to explain how I view this.
Anyone out there have a better term?