How can I make sure the axis start where there is actual data and not as much white space in a continuous plotted line chart.

This can be achieved with the help of functionality called a fixed axis. create your report and then right-click on the axis and select the edit axis. Hereby default, the range will be selected as automatic and you need to select the radio button called fixed. Once the fixed radio button is selected, you will get an option to enter your own start and end axis range.