Finding knob-and-tube behind a wall is unsettling, and it is usually sold as an emergency. It rarely is. What it is, reliably, is an insurance problem and a capacity problem.
Circuits that matter first
Kitchen, bathroom and anything feeding a modern appliance load. Those carry the current the old wiring was never designed for.
Then the rest, as the walls open
If you are renovating a room anyway, rewire it then. Staged over a few years this costs a fraction of a single whole-home job.