Yes, studded tyres may always be used, regardless of the date, if winter road conditions apply or are expected. However, you are never allowed to use studded tyres on streets where studded tyres are prohibited.
Winter road conditions apply when there is snow, ice, slush or frost on any part of the road. Keep in mind that the hard shoulder is also part of the road. In the event of a vehicle inspection, it is the police that determine whether wintry conditions apply at a particular location.