The 24-year-old this week stepped up his return from a second serious knee injury with a 25-minute run out in a training ground game at the Academy of Light.
Ross has always been keen not to put an exact timescale on when he will return to first team duties and says that remains the case.
Ross said: "I’ve been very consistent in that answer that I’ve never put a time frame on it.
"I’ve been consistent in my conversations with Duncan on that too, hence the reason he has responded so well and his progress has been so consistent.
"Touch wood, the work that has been done with him on the medical and sport science side has been fantastic and it’s allowed him to progress at this really steady rate. He feels good about himself.
"He played a little bit of an in-house bounce game and the next step will be getting him involved with the Under-23s and when he gets through that we start to assess when he could be involved in first team games.
"But there’s no definitive timeline on it."
* Bali Mumba has been called up to the England U18 squad to play in a four nation tournament in Spain next week.
Neil Dewsnip’s squad will head to Murcia for three games, kicking-off on Thursday 15 November against the Netherlands at the Pinatar Arena before taking on Republic of Ireland two days later and Belgium on Monday, November 19.
Sunderland midfielder Elliot Embleton - currently on loan at League Two Grimsby Town - has been named in the England U20 squad to face Germany on Monday, November 19 at Colchester.