The Belgium international returned to the starting lineup in the 3-0 defeat to Everton last week following a six-month absence through injury.
Villa travel to Queens Park Rangers tonight on the back of a four-game losing streak and it had been hoped that Benteke's return would galvanise the struggling Villans.
However, Lambert insists that the 22-year-old might require a run of around six games before getting back to his lethal best.
He told The Mirror: "Christian hasn't played for six months. It might take him half a dozen games to get up to speed, to really find his find his feet. The reality tells you that won't happen straight away.
"Because he's just coming back, there'll be times when you think: 'yes, he back to his old self' and others when he'll look like someone who's not played for a length of time, but when you put Benteke on your team sheet - it makes people think.
"There are still times when you think that and when he's fully back we've got a really good player there."
Benteke netted 34 times in his first two seasons at Villa Park.