How should i prepare my toddler for her 1st day to playgroup/pre school?

My experience is, my girl went inside and start playing on her own, hence teacher suggest that i wait outside, as it's 1/2 day for her during the 1st day. She adapt well for 1st week. 1st day, 1/2 day. 2nd day, also 1/2 day. 3rd day, teacher try to let her nap, but she don't nap, hence i pick her home. 4th day, teacher manage to let her nap. Hence it's a successful week. It's work out well on 1st week. 2nd week onwards, cry after she reach school. Teacher took awhile to coax her and i have to sneak out. Till now, my gmil send her to school, she never cry, but i send she will cry.. But she do enjoy the school though, guess it's really depend on the kids itself. My friend have the same situation as me too, other people send the kid to school is ok, but not her.