The response is provided based on the information you shared. It is not legal advice nor should this information be used to make a decision. It is highly recommended you speak with your chain of command, IG, and/or JAG before making any decisions.
Based on previous information: If the Soldier was not reasonably expected to be on duty and was not given an order “NOT” to drink the Soldier should not be tested until they would have normally reported for duty.
Example: Soldier leaves work at 5pm and is to return at 6am the next morning. Soldier is called into work at 1am and had no prior knowledge they would be required to come to work. The Soldier would not reasonably be tested until 6am because that is the time they would have normally been required to report. If the Soldier is still drunk at 6am then they could be charged.