Just make all clocks that are connected to internet run 0.1% faster / slower until you are at UTC+12 and in about one and a half years everyone should be caught up. People will only have to change their mechanical watches by 1.4 minutes every day, so it should hardly be noticeable
Just make all clocks that are connected to internet run 0.1% faster / slower until you are at UTC+12 and in about one and a half years everyone should be caught up. People will only have to change their mechanical watches by 1.4 minutes every day, so it should hardly be noticeable