Well given that FR announced their BFS-LGW route in the middle of January last year, I don't find it unreasonable to announce the new London route at the start of February, especially given that many business people flying to London would be booking flights relatively late.
Also, I don't think that the people of the North West have the right to potentially complain about the new flights being announced so close to the start date; they're lucky that the Government has provided financial support for a route to an airport which should have been closed years ago. The NI taxpayers have been flogging a dead horse for years and it's clear that if a PSO is required for flights to the capital, the route should be axed.