The French hitman hasn't made his full debut for Leeds United yet.
The Elland Road club signed the 22-year-old French striker on a half-season loan from Leipzig in the January transfer window.
But Augustin hasn't hit the ground running under Leeds boss Marcelo Bielsa, who is yet to give him a full debut.
Bielsa continues to start Patrick Bamford up front ahead of the young marksman, much to the frustration of fans who have seen the Englishman score only twice since December.
Leeds midfielder Kalvin Phillips said on Tuesday that Augustin isn't on Bamford's level with regards to fitness and pressing just yet.
And former Whites forward Whelan, speaking to BBC Radio Leeds, says that it could take at least eight weeks for Augustin to adjust.
He said: "He just looks sluggish. He looks like he is fighting his fitness, fighting to find pace. You have to manage him very carefully, but at the same time, we have brought a player into the club that is not going to hit the ground running and it is going to take him two months minimum and that could cost us."
It definitely could cost Leeds, who need him scoring goals as soon as possible.
United had an 11-point cushion in the automatic promotion places before the turn of the year, but now they're second only on goal difference.
Bielsa's side are really, really struggling for form and goals and by the time Augustin gets into the swing of things in West Yorkshire, you wonder if they could be already consigned to the playoffs.
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