The Irish international was back at Wast Hills on Monday following a long leave of absence, which was granted for personal reasons.
"Keith's been working with the fitness coaches and they've been delighted with his fitness," said the Blues boss. "I think he's a naturally fit lad anyway, he doesn't need much work.
"We will be deciding in the coming days when we integrate back into the group and whether we bring him straight back into the first team or we leave him with the development group for a while.
"But, as I said, we're not going to force him into coming and doing things too quickly. He will be in on the decision making and when to up the workload in terms of moving from fitness training into football training. It might be a week, it might be a month; there's no timescale on it."