Shafeeq:
Yes, you can definitely import the Invoice date.
Three steps: (1) add the Invoice date as a column to your import file (placed among the other header fields) then (2) modify the Import template to include the field "Hdr-Transaction Date" in the appropriate position then (3) while that field is highlighted, look at the bottom of the Import screen and select the right date format.
Note: If you are using the template named "Invoices Default" or you don't see "Hdr-Transaction Date" as an option, first select the tab named "Field Defaults" and unselect the field "Hdr-Transaction Date" (highlight the field then click on the arrow that points to the left). Now you can go back to the tab named 'Import Field Selection" and "Hdr-Transaction Date" will be available to select.
Here is a 5-minute YouTube video on Adagio importing:
Video on Import Templates Imports can be finicky (to quote someone), so if you have troubles with the process, ask your Adagio consultant for guidance.