using the record player in the ministry becomes a #1 hit

You may have heard that at one time Jehovah's Witnesses used the portable phonograph in the door-to-door ministry. So, when did it start?
From the "Divine Purpose" book page 138.
"I'm glad you remembered that, because the work the Society had begun with transcription records proved even more effective than the radio work had been. In fact, the results in 1933 had been so promising that the Society began to produce another service the following year. That was the use of the portable phonograph and short recorded Bible lectures. These were 78-rpm discs with 41-minute talks."
So, 1933 it was tested in the field and put to full use in 1934.