Create a folder in the format year-month-day and save the screenshot

screenshot.gd

func screenshot():
  var img = get_viewport().get_texture().get_data()
  img.flip_y()
  var dir:Directory = Directory.new()
  var now = OS.get_date()
  var folder:String = 'user://screenshots/%s-%s-%s' % [now.year,now.month,now.day]
  dir.make_dir_recursive(folder)
  img.save_png(folder+'/%d.png' % OS.get_unix_time())