Scheduling a provider switch - lead time?

I'm looking to help someone switch providers - line and FTTC broadband package - but they don't live around the corner, so ideally the switch would happen when I am visiting and staying with them for a few days.

This would actually be a move from one BT Wholesale based provider to another, which I think might make things simpler.

I've got some vague memories of placing orders for broadband services and being able to nominate your desired go-live dates, but maybe I'm muddling that up with installation of a new line, or a house move, or a switch over from ADSL to VDSL/FTTC.

Is there a ruke-of-thumb lead time for such a switch? FTTC is already up and running on their line, so no need for an engineer visit to the local cabinet.

My thinking is that the new service could be ordered say the week before I visit.

(Essentially the assistance I'd provide is changing the router, reconfiguring it with their existing Wifi SSID and password and turning off any annoying 'smart connect' feature that might be present.)

Rules around migrations mean at least a 10 working day period for the resident to say no they did not order a migration.

Rule of thumb is around 3 weeks, so best thing to do is place migration order and once a go live date has been supplied plan to be there on that day (with a bit of leeway)

Much appreciated Mr Saffron. I'd quite forgotten about the 'anti-slamming' cooling off period. Am I right in thinking that the losing provider is actually obliged to send a letter by post?

Looks like the order had better get placed sooner rather than later. Ultimately it's not crucial that I'm there in person to set things up, it'd just makes things a bit easier if I was.

Cannot recall if obliged to use post or whether other communication methods are acceptable.

Even if sent by email does not change the time scales.

I've nominated a date a couple of times and the switch has taken place on that date or maybe a day late. Best to select Mon, Tue or Wed.