The 23-year-old has been out of action since suffering an Achilles injury around five months ago.
The Belgium international returned to training last week, but Lambert believes that Saturday's trip to Stamford Bridge will be too early for the forward.
"I'm not sure if [the Chelsea game] might be a bit early, but you're looking not too far after that I think," the club's official website quotes Lambert as saying.
"He has trained this past week with no ill effects. He will train again this week. We will see how he is, but he's not too far now."
Benteke has scored 29 goals since his arrival from Genk in 2012.