Depends on where you are and who is doing the work.
For instance, do they have the part or does it need to be ordered. Is it a Kenworth shop or have they done KW before. (Don't actually know if there is a difference between different trucks, not a mechanic.)
Such a shut down though is usually until fixed unless another truck is used to run with.
Best thing to do is ask the people doing the job, how long they think it will take to get your back on the road. (Then be mentally prepared for it to take another day, lol)
My experience with getting it done with Freightliner at Truckstop was same day, no problem. However, they had few customers that day in the shop and Freightliner parts are plentiful and usually on hand.