Where is minDate on membership start date set? Or can I change what minDate is set to?
minDate for these entities can be updated at Administer &gt; Customize Data and Screens &gt; Date Preferences, i.e, civicrm/admin/setting/preferences/date?action=reset=1

Click on Edit and update the Start Offset(minDate) to eg 30. This will default the membership start date to start from current year - 30.