I notice that this question doesn't have an answer yet.
I have recently subscribed to your monitoring service and I have the same question. To clarify it a bit more: When you look at "Performance monitoring" you will see a graphic that shows the measured values against a time scale. But there is no clear indication of what the time scale is. The only things you see are 2 timestamps with no clear relation to the whole graphic. In the current graphic it is not possible to tell wether you are looking at a 24 hour span or something else.
I would suggest that you put a time indication for the left and right part of the scale and some sensible intermediate values in between them.