How to enter journey start date?

[Dan Wheatley]

Hi
I'm attempting to create a journey plan with limited days per week travel (i.e. Monday and Friday for example) and would like to enter a start date for the journey to create an itinerary but I can't find where to enter it.  The planner tells me I have not done so, so it must be an option?
Thanks for your help
Dan

[Stephen Atty]

Under Trip Length settings pick the Start and end date option