Hi @MO4,
I think the easiest way will be to deactivate button until proper conditions. So the user will see the button but will not be able to press. You can use jQuery to do so. First, you need to find the id of the submit button and use the next code to deactivate/activate it:
// Disable #x
$( "#x" ).prop( "disabled", true );
// Enable #x
$( "#x" ).prop( "disabled", false );
You can use onchange event of the field that use in condition to make enabling/disabling of submit button automatic.