In chapter 8 it says:
It was when I stood before her, avoiding her eyes, that I took note of the surrounding objects in detail, and saw that her watch had stopped at twenty minutes to nine, and that a clock in the room had stopped at twenty minutes to nine.
So, this time of 8:40 is obviously significant. If you continue to watch as you read and notice the moment at which in this home it seems time has stopped you will put together a puzzle about why this time is so important.
At this point in the story, this woman is just freaky to Pip. Her dress, her home, her desire to see a young boy at play. But hang on to these pieces!