Watson, who sustained the injury during a non-contact play in practice, could return in some capacity for the Texans' organized team activities that span from mid-April until mid-June.
The 22-year-old initially was handed an eight-to-nine-month timeline for his rehab from his November surgery, which would have him set for training camp.
"(Watson is) doing a great job," O'Brien said Tuesday.
"He's been here every day, working hard to get better and I believe he's ahead of schedule. Exactly what he could do in OTAs, I wouldn't be able to tell you that now, but I do think there's a chance that he could be out there during OTAs doing something."
Watson tore the ACL in his left knee at Clemson, but went on to become the 12th overall pick of the 2017 draft.
He had thrown 16 touchdown passes in October alone, breaking Hall of Famer Dan Marino's 1983 NFL rookie record for most TD passes in a calendar month.
Watson was named NFL Offensive Player of the Month and AFC Offensive Rookie of the Month for October, when he had 1,171 yards passing and 145 yards rushing on 21 attempts with a touchdown.