How can I create early bird fees with Webform CiviCRM?
Add a field of type Date to the webform -> set it to default: now - and set it such that start date = now and end date = now; deselect the Enable popup calendar

Conditionals: example:

Hide the date field with CSS and hide your element with CSS - as you can see above mine is called today:



.webform-component--today {
  display: none; 
}