I’m going to Recruiter school at FT Knox KY. How difficult is the school? What regulations should I start studying?

I was a Recruiter and must say...you won't need to prepare...you'll get plenty of study time!! You'll be fine. A piece of advice...Never force anyone to enlist even if the Station Commander puts in the pressure. Just be yourself and LISTEN to your perspective candidates and then you'll realize early if military service is for them. They join because they want to and not because you want them to.

Graduation is on Friday I pass

Know your competition meaning know what all services can and can't do when it comes to enlistment contracts. I had every services so if I needed evidence it was available. Recruiting is a hard but fulfilling assignment.

42 very long missions in US Army Recruiting in Scottsdale AZ
<Gold Badge with 3x SS; Assistant Station Commander for 18 missions>

The Schoolhouse will teach you the very (..and I do mean VERY basic) things you will actually need to know. Once you arrive at your Recruiting Station your teammates will school you on the rest of what you will need to know. Memorizing manuals will save your hide, and knowing your competition will give you an edge, but in the end it is by "Being the Soldier the potential applicant wants to be" that will be the greatest asset to your continuing success and/or failure.

-----BE-KNOW-DO-----
Be the example of the NCO your soldiers would look up to, the applicants will do the same
Know when you are wasting your time on an applicant that simply cannot or will not go.
Do in-depth Pre-Qualification starting from the very first contact with the applicant.

Personal suggestion;
Use a 3-minute egg timer while you are 'Red Time'...if you cannot get the appointment scheduled in three minutes you probably wont in the next few minutes either.
Always remember "Eye Contact is preferable to physical contact"
Never forget, you will be a HERO at the end of the month and a ZERO at the start of every month

One last recommendation
Study your MOS-Q FM's in your free time, do your PT every day without fail, and remind yourself in the mirror every single morning... "I am (fill in whatever your MOS is) and I am returning to the US Army that I love after this is over". Far too many of the Recruiters around me did not do this and after three years in Recruiting decided to remain in Recruiting instead of returning to the Infantry like I did.

Get an ATRRS school house information, that should give you info that you might need.