The planning for the new routes is in place, and they have probably designed most of the schedules, subject to tweaks from service changes that may have happened in the interim. (For example a service improvement on a route affected by Line 5 that was implemented after the new, post-line-5 version was already written.) First problem is that the process of posting the new work arrangements for operators and signing up the crews has about a two month lead time. There is also the issue of whether there will be a "big bang" with both lines opening at once, or two smaller upheavals. Obviously Eglinton is the bigger of the two. Maps of planned routes for both the Line 5 and 6 openings have been around for ages and have been through rounds of public consultation. Changes in routes may also trigger route allocations and staffing changes at divisions. This is not a trivial process. It would not matter whether the TTC was the operator for Line 5 or not, there would still be a big upheaval on the bus network. At least as the line's operator and with the associated training, the TTC has some view into what is happening. For budget planning purposes the TTC has to pick a "go live" date whether it actually happens or not. They had extra money for service at the end of 2024 as they had planned on a September startup.