If you need to run a report for an unusual date range you can create a custom date range. This will allow you to re-use this range again and for your colleagues / team members to use this range as well.
From the report builder, click 'New Custom Date range'.
Here you can also edit an existing range.
Choose either a fixed or dynamic range and give it a name. Once you've saved it you'll see it as an option from the date picker window.