Well, by taking a look at him/her it was a hard choice to make.
Number 1 : There are barrings on top of the head. If they go all the way down to the nose/cere she/he is a baby still.
Number 2 : Their nose/cere which is located above the mouth can be either pink or blue. Blue means that the keet is a male and if it is pink she is a female.
It looks too hard to tell right now since of a smaller picture and since you just brought him/her home.
It may be too early to tell. Keep us updated with pictures.