IMHO from what I've found to-date up to very early L5 for the gold pieces, probably slightly earlier for the bi-metal but not much beyond L424. The reason for the slightly later L5 for 16528's, is that I came across them over 10 years ago before floating cosmographs were really well known and at the time still considered used modern pieces not as now deemed vintage, collectible and rising prices accordingly and from memory both were close in serial number range and had white dials. I wish I had taken further details at the time.