Hiya @whenisayjump (James) & Welcome To The Cuckoo Community & As Part Of The Flock
The Move Home System from within Your Cuckoo Account is just the same form that is used when you initially sign up just slightly modified so this is why its giving you the 14 day window for preparing the line ready for your arrival at the new address.
Try to make your go live date on the form land the day before you move in as it can be anytime during the final transfer day that the line will go live.
So if you want to move in on the 12th as you mentioned above have it go live on the 11th instead providing it falls on a monday to friday date and also Openreach Engineers can only routinely be dispatched Monday to Friday to a customer if there is any availability.
However there are some special rare requirements where a Saturday visit can be made so maybe the system wants to dispatch/prepare an engineer on monday reading from what you have said if friday is full.
Plusnet have the same systems that Cuckoo do and if theres an Active Openreach Line in the property then this will be the same line that your services will come down whether it will be Plusnet who prepares it for you on a 12/18/24 month contract or Cuckoo on the 30 Day Rolling Contract Terms.
I suspect the engineer is put on emergency standby on the day as well just incase anything goes
wrong and if they are needed you will get a text message from “SiteVisit” if this is the case as the team want to get it resolved ASAP and get you connected.
Also a Cuckoo Home Move can only be done once a year for free otherwise there will be extra fees that will need to be paid,that saying most people like to settle into a new property for as long as they can.
Once the line is prepared and the Home Move Order is complete you simply open the door to your new home and 1st priority is to plug the router in to the master socket or with the supplied microfilter dongle and lead (depending on your socket type) and then 2nd Priority is to fill and plug in the kettle to make a drink while you wait for the router to sync up and then your off on your new surfing and streaming journey.
Everything should be simples as
that famous meercat says.
Hope this makes more sense than the online forms.