Have you tried using the defaultDate
option? From the docs:
Set the date to highlight on first opening if the field is blank. Specify either an actual date via a Date object or as a string in the current dateFormat, or a number of days from today (e.g. +7) or a string of values and periods ('y' for years, 'm' for months, 'w' for weeks, 'd' for days, e.g. '+1m +7d'), or null for today.
Code examples
Initialize a datepicker with the defaultDate option specified.
$( ".selector" ).datepicker({ defaultDate: +7 });