I will have to take the plunge.
Learning the material for the test won't be that hard. The technical part of it is pretty basic & you probably know most of it already. The rest is mostly FCC (and as you saw ITU) regulations, which actually make sense once the basic concepts are understood, plus some questions about operating practice that are pretty much common sense.
But go with confidence you'll bring something home, and stay until you quit passing tests or run out of tests to pass.
For a first license you have to wait until a callsign is issued and you can get that from the FCC webstite within a few days and begin operating before the license arrives in the mail.
When you upgrade your new privileges are effective the moment your examiners sign your CSCE.