"There's been a quite a dramatic improvement in Will's condition and the way things are looking at the moment he should be back training before the end of the week," Calderwood told Forest's official website.
"The Carlisle game on Monday might come too quickly for him but if all goes well we would certainly look to have him back in contention sooner rather than later.
"There seemed to be a story going around that we were looking to send Will back to Watford but that's certainly not the case.
"As he is still Watford's player we were keen to inform them of his injury out of courtesy."