Jayson Tatum’s return is starting to feel less like an abstract idea and more like an eventual reality.

For the first time since suffering a torn Achilles, the Celtics star has reportedly reached a meaningful checkpoint in his rehab, progressing to 5-on-5 work as he continues to ramp up toward a full return.

According to ESPN’s Shams Charania, Tatum has been a “full go” in scrimmages during recent team practices, including workouts held during Boston’s Western Conference road trip.

It’s a significant step, even if Tatum himself is keeping the details close to the vest.

“There was a little five-on-five,” Tatum said Saturday. “It’s tough to go into detail of every single thing I do every day. But I will say getting acclimated more and doing limited things with some of the guys out there. It’s all a part of the rehab.”

That measured tone has been consistent throughout his recovery.

The Celtics have made it clear from the start that this process will be dictated by Tatum’s comfort level, not an external timeline, and the latest update reinforces that approach.

Speaking on ESPN’s NBA Today, Charania outlined what the next phase looks like as Tatum increases his workload.

“Right now, it’s about him continuing to put in the time, continuing to get his conditioning up and that comes through a number of practices and scrimmages,” said the NBA’s top insider. “There are two elements right now at play. One is increasing the strength in both of his calves off of that Achilles tendon injury and the big hurdle of all this is getting 100 percent there on the mental side. Getting the confidence in his leg fully when he’s back.

“The common theme that I’ve gotten around Jayson Tatum is he will be back on the floor when ‘JT feels like JT.’ The Celtics have continued to let him lead that process. He’s in the driver’s seat. They will take Jayson Tatum’s lead as far as when he feels like he’s ready and cleared.”

That last part is the key.

For all the physical benchmarks - the scrimmages, the conditioning work, the strength building - the mental hurdle often proves just as important in a recovery like this. Feeling like yourself again isn’t something you can rush, and Boston appears committed to letting that confidence come naturally.

Tatum hasn’t offered any hints about a target return date, and he declined again to put a timeline on things when speaking with reporters over the weekend. He did, however, acknowledge the seriousness of the process and the mindset he’s taken throughout it.

“I’m just taking it one day at a time,” Tatum told reporters Saturday. “It’s something that’s very serious, the injury that I have. It’s just a long journey. For me, it’s just a lot easier to take it one day at a time.”

His progression has come against the backdrop of strong team play. The Celtics have won nine of their last 10 games as Tatum continues to work his way back, giving the team some breathing room to remain patient.

Boston has also made subtle roster adjustments, including shifting Payton Pritchard back to the bench after trading Anfernee Simons for Nikola Vucevic. Moves like these could help smooth the transition whenever Tatum is ready to return.

For now, the focus remains on steady progress rather than countdowns.

The scrimmages are a sign that the next phase has begun, but the finish line will ultimately be defined by one simple benchmark:

When JT feels like JT again.

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Tom Carroll is a contributor for Roundtable, with boots-on-the-ground coverage of all things Boston sports. He's a senior digital content producer for WEEI.com, and a native of Lincoln, RI.