Turnbull (20) would have joined the Hoops in a stunning transfer had he not failed a medical due to a knee problem which has subsequently been operated on."We're not putting any timescale on it (Turnbull's return to the first team)," Robbo said. "We're not putting any pressure on David first and foremost."I think he goes back to the specialist on Monday to get the all clear to step it up a bit."What that stepping up means and how quickly it happens I'll leave that to the medical side of things."He's doing well, everything's going to plan as we speak at the moment."And I'm waiting on that Monday to kick on a bit further."Despite star man Turnbull's absence, the Steelmen have made a fine start to the season as they sit fifth in the Scottish Premiership ahead of this Saturday's league trip to face Hearts at Tynecastle."It's very early on in the season," Robbo added."We've had to replace a number of players, David being one of them due to injury."We lost a lot of goals out of the team with David and Jake Hastie leaving."If you look at the amount of players we've lost I'm pleased that we've started the season well."We've won six, drawn one and lost two."It's been a good start for us considering the amount of changes that we had."With David missing, we've replaced him so far. Liam (Donnelly) has come in and done well."It would be an even stronger team with David in it. But I think that's a little bit away yet."