The French defender has been out of action since December last year due to a serious knee injury, but is on the road to recovery at the moment.
He is set to join the squad for training this month and is expected to get back into the team soon to give a major boost to Ange Postecoglou’s defensive options.
However, Ferguson is well aware about returning from serious long-term injuries and stressed that Celtic need to be very careful while introducing him back into the team in the coming weeks.
He insisted that Jullien’s form will be up and down once he returns as it will take him to settle down into the rhythm of playing regular first-team football again at a club of Celtic’s stature.
The former midfielder said on the Go Radio Football Show: “In terms of Jullien, they need to be wary.
“He has been out for a long time, there needs to be a level of patience. I know what it’s like to be out with long-term injuries.
“When you come back you get that initial energy and then you have that slight dip.
“It is going to take him a bit of time.
“He has missed a hell of a lot of football.”
The defence has been a problem for Celtic and the club may be hoping that Jullien’s return will solve some of the issues.