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.
Source : PA
Source: PA