Cargill has not appeared for the Gills following his move to the League One team at the end of August.
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."