As a commander, what should I expect from the new IET Soldiers during the first 72 hrs?

Expect them to go thru a major adjustment period, emotionally. You'll likely have a bunch of folks that want to quit, but don't let them. They'll be fine after the first week. The few that still want to quit will self-identify some conditions that existed prior to service.

Remember you are the Company Commander. Let your Drill Instructors do their job, you are new and if you listen to your DIs, you will be on the right road to success. These DIs are the US Army's best. They have a product to produce in a limit amount of time. It's always wise to observe what's going on in your unit and not get too involved in everyday affairs. Meet your unit in the first 72 hours and give them an overview of what you expect as as well as what they can expect from you. Realize many are young and somewhat afraid initially but they must understand the rules first hand. Be tough, they are expecting it, don't be their buddy. And remember " Familiarity will cost you your career. Hope you have a wonderful cycle. I have commanded a OSUT company in 1980 and it can be a rewarding job, but also the Battalion Commander wants high marks on your Cycle Report Card.