Hipwood was expected to miss a majority of the 2022 season following the diagnosis, placing the Lions' forward structure with the prospect of challenging for the flag without one half of their twin tall pairing of Hipwood and Joe Daniher.
Despite the initial signs, the 24-year-old has been able to tick multiple boxes ahead of schedule in his recovery from the knee injury, which was sustained in Round 17 against the Saints last season.
Hipwood has already hit the track as part of the Lions' pre-season training regime, however the tall forward is absent from any contact drills as he continues his rehabilitation.
"He'd like to do more probably if you'd let him," Fagan said, per AAP.
"He thinks he's going to be back for the start of the season. He won't be but he might not be too far in.
"May, end of May, is probably a reasonable time frame for him to get back if he doesn't have any hiccups.
"It's been pretty straightforward to this stage with no setbacks."
Should Hipwood be deemed fit to feature for the Lions in May, the athletic forward could line up against the Swans on May 1.
The Lions are scheduled to clash with the Eagles and Crows in Rounds 8 and 9 in the following weeks, with the AFL yet to confirm fixtures from Round 10 onwards.
Brisbane will still need to combat the loss of Hipwood for the opening months of the 2022 season, with recruit Darcy Fort seen as a chance to partner Daniher in attack.
The Lions are set to be bolstered by the returns of Cam Rayner and Noah Answerth this season, with the pair having missed the entirety of last season due to knee and groin complaints respectively.