I think I had read somewhere that he had not exactly "acquired" it - well, he didn't "buy" it. It was a gift from someone (maybe Baldwin?) and Brian was so pleased with it that he wanted to bring it to Hawaii for the live shows. My guess is that he must have got it between a week and a month before the Hawaii shows, otherwise the "excitement" would have passed and he wouldn't have brought it there.
By the way, I have a question about this Baldwin theater organ. What model was it? I think it was either a HT2 or a HT2-R but I'm not sure...