I ordered yesterday and Sky booked it for 23rd August but that was changed today to 24th August by Openreach.
Has your exchange recently gone live? if so there are other cabinets to bring online and also a surge in broadband orders to install.
Until fibre becomes a self install product I think a 2-3 week timeline is fine.
Sky Broadband Unlimited
Ashington (Northumberland) Exchange
Fibre install date 23/08/2012