Even Sterling Shepard didn’t expect this much progress this soon.

The Giants’ new No. 1 wide receiver hoped his fractured left thumb wouldn’t keep him out of the regular season opener Sept. 8 against the Cowboys. But three weeks ago, after he suffered the injury on the first day of training camp, there were doubts how it would heal.

“At first I was a little bit nervous,” he said.

On Sunday, Shepard was able to practice like any other wide receiver — without the yellow no-contact jersey he’s been sporting all summer — for the first time since the injury. The thumb isn’t 100 percent — Shepard admitted he isn’t ready to play in Thursday’s third preseason game at Cincinnati, which likely means he won’t appear in any of the team’s four preseason contests — but is further along than he could’ve imagined it would be at this point.

“It’s actually healed up pretty fast and … I’m feeling good,” said Shepard, who is still wearing a splint and has been practicing most of training camp despite the injury. “I wouldn’t say I’m all the way back, but I’m pretty close. I’m where I need to be. I feel good about that.”

Added coach Pat Shurmur: “He’s been cleared all along to be out here. It’s just the next step in the process. He’s fine.”

Shepard is wearing a small pad underneath the splint, which he hopes to get rid of soon, to alleviate discomfort when he catches the ball. He ditched the yellow jersey for a few reasons: Team doctors said it wasn’t needed anymore, and he was still getting hit on occasion anyway.

“It’s not that big of a difference,” said the 5-foot-10 Shepard, the fourth-year pro who caught 66 passes for 872 yards and four touchdowns a year ago. “I guess it makes guys more cautious of hitting you [when you have the yellow jersey on]. I kind of need that contact.”

It’s more symbolic than anything else, another step in overcoming the injury that was once thought could cost him a significant portion of the early part of the season. Instead, Shepard seems likely to be out there in Dallas in a few weeks.

“I don’t see anything that can hold me back right now, unless something was to happen in practice,” he said. “I’m on pace.”

Of course, this wasn’t how the Giants imagined the summer going for the 25-year-old. The team’s top target at wide receiver now that Odell Beckham Jr. is in Cleveland, Shepard will be critical to the offense, especially because Golden Tate will be out the first four games for violating the league’s performance-enhancing substance policy. Shepard signed a four-year, $41 million extension in the offseason and will be counted on to produce as he faces the opposition’s top defensive backs weekly and leads an inexperienced unit early on.

“The [last four] games of last season, I was in the same situation [with Beckham out with a bruised quad]. I felt like I handled it pretty well, so I imagine it being the same way,” he said. “I’m going to go out and be myself and let everything take care of itself.

“I’ll be bouncing around a little more than I would if [Tate were active]. I kind of expected that going into the season anyway. My mindset is on that, and it should be fun.”