Maynard has not featured for the Robins this season after undergoing knee surgery in August, but although he has returned to light training, he will not feature in a behind-closed-doors reserve-team game.
Millen said: "I've set-up a game because quite a few players need a run out, but Nicky will not be involved in that.
"It's too early for him and he needs to build his training up before he can think about playing a game.
"He's making progress, but he's not even back training with the squad yet. Nicky is still working with the physios, but at least he's back out on the grass again and it's nice to see him at the training ground."
Source: PA
Source: PA