Not too sure, maybe around September when all the kids are back at school. I'm going to go by road (3 days) using b roads and country lanes or canal (4 days).
I'd be getting on the canal at Scarisbrick (between Southport and Ormskirk).
Looked at my route on www.canalplan.org and the route from Scarisbrick Bridge No 27a to the Limehouse Basin Entrance.
Total distance is 279.98 miles and 207 locks. There are at least 19 moveable bridges of which 4 are usually left open; 77 small aqueducts or underbridges and 9 tunnels (Deansgate Tunnel, Woodley Tunnel (176 yards long), Hyde Bank Tunnel (308 yards long), Harecastle Tunnel (2919 yards long) [see navigational note 1 below], Newbold Tunnel (250 yards long), Braunston Tunnel (2042 yards long), Blisworth Tunnel (3056 yards long), Maida Hill Tunnel (272 yards long) and Islington Tunnel (960 yards long)).
This is made up of 134.18 miles of narrow canals; 145.80 miles of broad canals; 87 narrow locks; 120 broad locks.
Not sure how busy or what the majority of the towpaths are like but I'd be looking at doing 70 miles per day.