My son is only 5 but started taking my nephew with me a few yrs ago, he just turned 19.
He had done some hunting but not a lot. I started him on the ground and was close by, and now have him in a stand. I kept an eye on him at a distance, and always told him where I would be. Last yr was the first time we hunted where we knew where each other was but couldn't see each other.
Biggest thing is safety, make sure he is wearing his harness, uses a pull up rope and uses his head. Have a general idea of where you both will be.
Have a set time to make contact with you or to be at camp. Since you are using text messages have him text you that he is sitting later or is done for the day. If he gets lost or off the path to stop walking and to make contact with you.
He sounds mature for his age and makes some great choices from what you said. He has that thanks to you and your teachings. Sooner or later you are going to have let him hunt solo, ask him what his opinion is and give it a try.