Hi,
First of all set the element to “hidden on load” in the properties panel, then you can show it using:
$w("#myElement").show();
In order to show the button, the user must submit data every time he visits the page? or only once?
If the user has to submit data every time, show the button after the insert function.
If the user can submit only once to see the button add a query to the onReady function and check if the user already submitted.
Good luck 