The Chile international has been struggling with a knee injury in the early weeks of the season, and came off the bench for the final 15 minutes of Juve's 1-0 win at Milan on Saturday.
With Allegri's men due to host Cesena on Wednesday, former Milan boss Allegri says Vidal is nearing full fitness, but will remain cautious in how they re-introduce him to the fold.
"Vidal has been training with the team for the past three or four days, but he's not 100 per cent and he needs playing time," he said in a press conference on Tuesday.
"We are in a situation where unfortunately we have players who have been injured and have missed training sessions."
Allegri also provided updates on the likes of Alvaro Morata, Andrea Barzagli, Martin Caceres and Andrea Pirlo, who have all been suffering from various ailments in recent weeks.
"Morata? I'd like to see him play 90 minutes, as he's a player with great quality, but let's not forget he only returned against Udinese after a month out. We need to take things slowly," he added.
"Andrea Barzagli will return on October 1. I had to have him in the squad for Udinese to make up the numbers.
"Caceres' injury is nothing serious and he should be available for the Atletico [Madrid] game [in the UEFA Champions League on October 1]. Pirlo will have a fitness test this week, but he's already training with the ball."
Allegri has made a positive start to his reign as Juve coach so far, winning four out of four matches in all competitions without conceding a goal, but the 47-year-old warned that Wednesday's opponents would be no pushover.
"They are in a good moment of form, they give away little, in three games they have only allowed nine corner kicks and have defended well," he continued.
"To win championships you need to win particularly against the smaller sides so as to head into direct clashes with rivals in a strong position.
"I will not change everything in the team - we are at the beginning of the season and I do not need to change anyone to catch their breath."
