The latest edition of Antiquity carries an important article by Gordon Noble of the Northern Picts project and others, arguing from recent archaeology and dating evidence that the carving of Pictish symbols began in the 3rd or 4th century AD – a couple of hundred years earlier than has been generally thought. They include Wemyss as one of the sites where such carvings began. You can read it all for free here:

https://www.cambridge.org/…/4F09B9C943A1C29F226…/core-reader