Yes, Six weeks is how long the 1st class Machin definitives in Royal Mail red have been available, and many of those are still not in every Post Office branch.
But already Richard has reported that the retail booklet of 6 has appeared with a 2013 year code of M13L
These have phosphor bands short at the foot, without which they might have remained in the shop, as he was not expecting to see a new year code as soon as this.
It does pay to keep your eyes peeled! We expect that this will be quite common at retail outlets, whilst the M12L version may not appear on the streets but only from Tallents House. It is also quite possible that the Bureau has sufficient stock of M12L for all eventualities and will not get the M13L version for some months.
Only time will tell! We await your reports.
If you find M13L or MA13 stamps please let us know whether they are from Post Offices, Tallents House, or other retail outlets. Thanks!
ROC ~ Rooster ATM FDC - Republic of China (Taiwan) Rooster ATM FDC, posted on February 23, 2017 from Xansia White Rooster postal agency.