Set start date/month for Date Picker

When a user clicks on the form it asks some questions including 2 dates, like arrival date and departure date. I would like to have the Date Picker start in the month the event takes place instead of showing a calendar starting at today's date. I read the documentation and I see I can add some Advance Date Configuration code following the flatpickr js standard. I see I can use minDate to specify the minimum date that a user can start picking from. Perfect, but I can't get it to work. I follow the documented FF example and visited the flatpickr site to see how to code it. I have tried various was of coding it but can't get anything to work. Does this feature work? Yes, I have selected the input date field first and then add the code.

I have tried

{
"locale": {
"minDate": "2026-09-01"
}
}

{
"locale": {
minDate: "2026-09"
}
}

{
"locale": {
"minDate": "2026-09"
}
}

{
"locale": {
minDate: "2026-09"
}
}