I have worked in a variety of locations around the world and I would agree with Yakkity...don't descend below your last assigned altitude until cleared for an approach. In the case of an ILS you should maintain that altitude until capturing the glideslope and then continuing descent on the glidepath.
ie ZZZ fly heading ??? to intercept the localiser, descend 3000', cleared ILS (or ILS approach, or ILS final)Rwy--