Ish, but that's also dependent on the timing of the handover.
The TTC has traditionally operated any new rapid transit service for 2 board periods before opening it to paying passengers, with each board period being 6 weeks (and so, about 3 months). (There is a 2 week board period over Christmas, but we're not going to count that - and neither do they.)
If the line was handed over close to the end of a board period, then the TTC could in theory start their work right away and have it open closer to that 3 month number.
But if the line is handed over well into a board period, than yes, it would be closer to 4 months.
Dan