Cody McDonald may be banging in the goals for Gillingham – but manager Paul Lambert has warned that the gulf between League Two and the Championship is vast.

McDonald – on loan at the Priestfield Stadium for the season – has scored six goals in his last seven games for the Kent side, earning himself the Player of the Month award for the division. But Lambert says no one should assume the 22-year-old can repeat the trick higher up the footballing ladder.

'You've got to remember if the step up from League One into the Championship was an absolute breeze Grant (Holt) and Chrissy (Martin) and Wes (Hoolahan) would have been on about 90 goals by now,' he said. 'It's different, you can't compare any league. If Norwich were ever lucky to go up to the next league it goes up again, the bar always raises, it always does. Cody is doing great at Gillingham, really great, scoring goals for fun, playing really well, but you have got to remember the gulf. The gulf is huge.

'That's me being realistic, I'm not going to pull the wool over people's eyes and tell them something different. You can ask any of our lads in the dressing room at the minute – the difference between League One and the Championship is big. You get punished quicker, you have got to score when you're on top.'

McDonald has scored 17 times in 26 appearances and Lambert says the loan is doing what it was intended to do.

'He came from Dartford to Norwich, which is a huge jump in the first place, but he was behind in the pecking order behind Grant and Chris and the way those two were performing, and Wes, in League One, nobody would have broken into it,' Lambert said. 'He needed games, he needed to go and get his confidence up and get goals, which he has done.'

Meanwhile, Oli Johnson's loan spell at Yeovil has been extended to April 16 – with City having a 24-hour recall clause.

• City's Championship clash with Nottingham Forest at Carrow Road has been brought forward a day to Friday, April 15 (7.45pm kick-off) after being chosen for live coverage by Sky Sports. The Canaries now face the prospect of three live dates in the space of little over a month – with the home game with Bristol City (March 14) and the trip to Swansea (April 9) also being selected by Sky.