Hojlund and Mount have returned to training this week after recovering from hamstring problems, and could be in contention for Saturday's trip to Crystal Palace.
But Ten Hag will treat them carefully after learning the lessons from last season when he had to bring players back too soon.
Mount missed 30 games and Hojlund had three lay-offs as United suffered with 66 separate cases of injury and illness.
'You have to be careful. In top football you always go to boundaries,' Ten Hag said.
Erik ten Hag admitted he 'overloaded' Manchester United players due to his injury headache
'It's not avoidable but when you have a full squad available then it's easier to manage the load. When you are in circumstances like last season and there is a need to play, we have to overload them. We hope we can integrate them in a very careful way.
'It's very good news they are back on the pitch, they are back in team training. We have to decide whether they are fit enough to start, but it is very pleasing they are fit and back in the squad. We have many games in this block, so we are very pleased.
'We have to make the final call. They did a couple of training sessions, we have to see the recover and tomorrow they will make the final call.'