About 21ish, ie after university.
The parents are probably thinking of suiters but of course she finds her own match.
If she doesn't then her parents recommend her someone, she meets him and says whether she likes him or not.
If she does find someone then they just meet the parents and get engaged.
you get married whenever your ready.
Its very stereotypical to think that Arranged Marriages are the only ways in which Muslims get married.
Majority of the people I know married in love.