How old was your toddler before they made an actual friend?

Amelia loves daycare, but I am a bit worried that she is not really making friends (do they even comprehend how to at this age?) There is one girl there on one of her days that she likes and talks about but even then she goes up says hi and then off she goes to play by herself. She watches the others play like she wants to join but just stands back. She is an extremely polite girl. She has great manners, does not snatch but if someone snatches from her she does'nt do anything just finds something else.

It actually made me teary this morning when I dropped her off. I stood where she could not see me a watched her for 10 minutes.