It might be larger than you think. Just making a new bathroom in an existing space can take a couple of weeks, and your guys have to do demo, break through a wall, build exterior walls (inside and out), run new plumbing and electrical (and have them inspected), and then finish the interior. Probably a month, if everything is lined up and ready to go (every tile and knob sitting in the hallway already), but realistically double or triple that when making your life plans.

Thank you so much for taking the time to respond!!

PS: This job is being done by a construction company. I would never attempt this myself.

sure, that's why I said "your guys" -- the people you hire. I presume that "your life plans" is how long you plan to live without that bathroom or close off part of the house for dust or whatever...

Any time you knock out exterior walls to enlarge house it is a big job.