O-Sensei said to me, "Takahashi-san, come to Iwama. I will talk to you about aikido," so I went to Iwama every month. From April of 1958 through the beginning of 1961, I visited Iwama once a month to listen to O-Sensei's lectures. Then I wrote them down in manuscript form at home and went back to O-Sensei again with them for review. After I obtained his approval, I published them in our publication, Byakko.
According to this evidence, from April 1958 through to the beginning of 1961 at least, Osensei was clearly living in Iwama and Takahashi-san was able to visit him there once a month.