Private alert box on redirected confirmation page

Now I do have a form where users (non-registered) can create a page. The user will be redirected to the newly created page by using the 'redirect' option in Confirmation tab in form settings. The url of the newly created page contains the Entry ID. So all I need to do is add http://www.example.com/newpage{entry_id} in the url field.

So far so good. After submitting user get redirected to the newly created page, Yihaah!

But now I want that same user, when he gets to that page he created to see a 'private' message in an alert box or otherwise which he can close or will dissapear the next visit or after a certain time.

NOTE: I am not looking for a browser cookie based first visit alert box which will be shown to all visitors who visits that page for the first time.

Is it possible for ONLY that same user (without being registered) to see that alert message on the page he just created and was directed to after submitting a Gravityform?

I've seen the option for adding query strings, but I am very unfamiliar with that.....is it possible to check if the page is loaded for the first time? (as in the counting of page views?)

Ok, thank you, I'll post it on the WP forum ;-)