Thank you very much for the help!!
But I don't want to reduce the end date because we have new data coming in everyday... Neither the start date because this dashboard will be used by several different customers.. They may have different start time...
Do you have any other way to achieve that?
Unfortunately, Tableau's functionality around the axises doesn't support a dynamic modification like that. It's more of "automatic and take what we give you" or "fixed and not-automatic".
You might play around with the formatting and see if you can make the spacing less obvious (removing the lines, for example, would help)