Have everyone grab the holsters and holster up and tuck into the appendix configuration with the grip exposed and the shirt tucked in.  Probably from XXX last week's suggested attire next week just to be simple, open shirts or shirts they generally carry with.  In fact maybe they bring a T-shirt and just a button up shirt or flannel type shirt.  XXX insert that in Day 3 finish.

Simple drill is to have them lift their shirt from the tucked position and place it over the pistol.  First of course have them do a few reps as far as just to make sure everyone's technique is good.  As far as thumb over the sight, withdraw your finger off the trigger, support hand engaged in the trigger guard and appropriate time.  Punching out, prepping the trigger and breaking off shots.  Probably have to reinforce some of the prep and do a quick little refresher drill, a trigger take up on prepping and then breaking the shot as soon as it's reasonably aligned within that defensive accuracy zone. 

Generally put forth the value proposition of concealment where open carry is allowed but it's probably not best practice.  Having a pistol is a piece of intelligence you want to keep to yourself and not necessarily broadcast in many contexts.  Officers have a lot of issues and security guards with exposed guns and it opens up a whole new set of issues and problems so it's best just to keep a gun concealed as best practice.  This is an effective buy-in so they have good buy-in of the need and importance to keep a pistol concealed if it's not common sense to them already. 

Video of Sample Class Related to This Block

The sample videos below are to help you see how this instruction is actually taught. Now, this is not the only way to instruct, but it is shown to give you an example.