“We’ll get them back on the grass tomorrow,” the Blades chief said.
"George (Baldock) has trained today fully, so we’ve got him back.”
Baldock picked up a hamstring injury against Bristol City on Easter Monday and has not played since.
England under-21 international Gibbs-White has scored 10 goals for Sheffield United this season and assisted a further eight.
The 22-year-old, who is on a season-long loan from Wolves, is the club’s second-highest scorer behind Billy Sharp.
Quizzed about a return date for Sharp, who has scored 15 times this term, Heckingbottom said: “It’s still too early. We are doing all we can.
"He went for some sugar injections last week, had a couple of days steady after that, we’ll see how he reacts now going forward.”
He added: "We know he’s going to do all he can and we know we’re going to do all we can in case we can extend the season.
"It’s better that than just sitting about thinking about next season.”
The eight-day gap has given Gibbs-White and Hourihane a better chance of making the game against Fulham, Heckingbottom said.
“With Conor and Morgan training tomorrow it’s done them the world of good,” he added.
"If it had been a quick turnaround they probably would have been in doubt, so that’s helped.”