The highly-rated Billing is yet to feature at first-team level this term after injuring an ankle in pre-season, although he has made an Under 23 appearance.
The Croatian who cost £200,000 from FC Ufa this summer has also had two outings with Frankie Bunn’s Under 23 side, one of them alongside Billing.
And he says there is plenty to come from both Danish prospect Billing, 20, and former Fortuna Dusseldorf man Paurevic, 25.
“They had less off-season than other players, so they are still in a situation of catching up,” explained the head coach.
“Neither are yet at the level they can be - this is no surprise to me - and they will both make progress.”
Wagner is making the most of the current international break which leaves Championship leaders Town without a game until the derby at Leeds United on Saturday week.
He explained: “We are in a good situation that we only have three players away with their national teams in (keeper) Danny Ward (Wales), Jon Gorenc Stankovic (Slovenia Under 21s) and Mooy).
“All the others are available to work here, but we will be careful about the schedules - we have one group who have played a lot since the start of the season and one who have played less.
“We will find the right course of action for each group and balance training and recovery. The friendly against Liverpool allows some players to get important minutes in their legs.”