You can use OpenOptions to change the default appearance of PDF file(s) when they are opened within Acrobat. Acrobat offers a built-in facility to control the default File Open options (via the File > Document Info option).
OK, so you want to stamp your document. Maybe you need to give reviewers some advice about the document's status or sensitivity. This tip from author Ted Padova demonstrates how to add stamps with the Stamp Tool along with related comments.