In The Giver, how long was Rosemary the Receiver before receiving her first bad memory?

Ten years before Jonas is selected for training, Rosemary had been in this same position. The Giver grew to love her, just as he loves Jonas. Rosemary was so eager to learn, and the Giver initially only gave her happy memories as he so loved the sound of her laughter. After five weeks of this, Rosemary really pressed the Giver to give her painful memories, too. She felt that it was her duty to share in the burden of the pain since this had been the job chosen for her. The Giver tries to explain his conflicted emotions about memories that he had to transmit to Rosemary:

"I didn't give her physical pain. But I gave her loneliness. And I gave her loss. I transferred a memory of a child taken from its parents. That was the first one. She appeared stunned at its end." (Chapter 18)

The Giver couldn't bear to impress physical pain on her, so he began with emotional pain, and he even chose those memories carefully at first. The Giver continued this painful part of Rosemary's training by always trying to mix in some happy memories with the painful ones. However, after an especially difficult training session, Rosemary stood up, kissed the Giver on the cheek, and left.
We know that Rosemary had those 5 weeks of happy memories in her training, and we know that she spent a short time working through some painful memories after that. We also know that when she was released, those painful memories came back to the community but that there were just a few of them. We can therefore guess that Rosemary's entire training likely lasted less than two months in total.