Despite a difficult, injury-hit start to life at Old Trafford, Falcao this week spelled out his desire to stay at the club beyond the end of the season.
The Colombian, who is on a season-long loan from Monaco, says he is settled in Manchester and happy at the club despite scoring just once in eight appearances.
Van Gaal will not be rushed into making a decision on whether to exercise his right to sign the player in a £43.5million deal though.
The United manager wants the former Porto and Atletico Madrid striker to prove his fitness and form first.
"He hasn't played so much," Van Gaal said when asked about the possibility of signing Falcao.
"You cannot see too much of a player if he doesn't train so much.
"He has been injured a lot of time
First you have to be fit.
"Now he shows fitness in the training sessions so maybe I shall select him (for Saturday's game at Aston Villa), maybe for the bench or the line up
Let's wait and see."
Falcao's last start came on October 5 when he scored his one and only goal for the club against Everton.
Van Gaal fielded teenage striker James Wilson ahead of the two-time Ballon d'Or nominee for last week's 3-0 win over Liverpool.
Van Gaal also endured a difficult start to life in England, but his team have turned a corner of late.
The win over Liverpool kept United in third position, eight points shy of leaders Chelsea.
United may have won six successive games, but so far their performances have not been up to scratch, Van Gaal admits.
Sir Alex Ferguson made a habit of winning titles on the back of occasionally scrappy displays, but Van Gaal, ever the perfectionist, wants to see performances as well as results.
"I am not only focused on results," said the Dutchman, who has won leagues in Holland, Spain and Germany.
"When I speak with Sir Alex (about playing badly and still winning), he says, 'It's not any problem, you have won', but for me it's also the performances that are very important because when you perform you shall win more and that's what I want to show to the fans.
"When you win six times in a row then the confidence is rising, but I am still looking for a game that is closer to the perfect game than we have given until now."
Van Gaal said British record signing Angel di Maria could return from a hamstring injury at Aston Villa.
"Maybe I shall select him on the bench or in the team
There's one training session to go," Van Gaal said of the £59.7million signing, who has missed the last three games.
Marouane Fellaini has been ruled out through illness.
Villa boss Paul Lambert believes United can still win the Barclays Premier League title this season despite a poor start to the campaign.
Van Gaal's side are clearly outsiders to lift the trophy after the Dutch coach's bedding-in period left them eight points behind leaders Chelsea, who are fighting it out with Manchester City at the top.
United have looked suspect in defence for much of the season so far but recent signs of improvement have convinced Lambert they should not be written off.
"They might not be able to lose many more games if they are going to win the title but they're certainly in with a shout," said the Villa boss.
"It is still a brilliant club with great players
The players they have brought in, there are not many teams in world football who can do that
They're a really good side."
The Red Devils have now won six matches in a row to significantly close the gap between themselves and their two rivals and now look a lot healthier than they did under David Moyes last season.
"Just because they've changed managers doesn't change my thinking of that football club," Lambert added.
"Chelsea and City have lost less games
But if United don't win it they will certainly have a big say in who does.
"If we win tomorrow it's good for us, that's the most important thing
We have to win for ourselves, it's got nothing to do with stopping United."
Villa will be without three players through suspension when they welcome Van Gaal's side.
On-loan Tom Cleverley, who would not have been allowed to play against his parent club anyway, is banned alongside Alan Hutton and Kieran Richardson.
Ashley Westwood (knee), Joe Cole (hamstring), Philippe Senderos (calf) and Nathan Baker (knee) are all injured, but captain Ron Vlaar and midfielder Fabian Delph are available after both returned from injury last weekend.
Source : PA
Source: PA