New Riverside Stadium boss Gordon Strachan has moved quickly to land the midfielder from Aston Villa.
"I played for Forest in the Championship last season so I know a little bit about what it's about, " said the 22-year-old.
"I know it's a lot quicker than the Premiership, that's for sure."
Elsewhere, the Reds' attractive looking fixture against West Bromwich Albion in January has been moved forward a day for television coverage.
The trip to The Hawthorns will now take place on Friday 8 January.