Cargill joined the League One side on loan in August but has yet to feature for the Gills due to an ankle ligament injury.
The 21-year-old is understood to be close to a return to training but Howe has urged the youngster not to risk further injury by rushing his recovery.
Howe told the Daily Echo: “Hopefully in the foreseeable future he’ll be back. But he has to make sure that when he declares he’s fit, he’s able to do himself justice at a good level.
“He has to perform well for his team. I don’t think he’ll be ready this week, but hopefully not far after.”