Your drill is fine. Just think about variety – there’s no one likely scenario.
Scotty1911 has posted a nice list.
Let me add shooting from cover, failure (to incapacitate) drills, and multiple targets.
While probably not possible, you should also think about pivots and turns, shooting while moving, shooting from a “downed officer” position (i.e. laying on the floor), dim light shooting, moving targets, and judgmental shooting (shoot/don’t shoot). Also think about shooting or moving and shooting from a sitting position or from a car.
Don’t forget to practice scanning during all drills.
And, very importantly, work on speed.
If you can’t fire from the holster at the range, you can practice drawing (and at least some of the other things listed above) at home with an unloaded firearm.
Also, very, very importantly (and not firearm specific), learn tactics (esp. awareness), mindset and such. Also learn your state’s laws regarding the use of deadly force.