You need to send out invitations immediately because from your previous posting, you are less than 2 weeks from your daughter's birthday! This may cause fewer people show up. But at her age, most parents will let their kids come. You can give them to your daughter and ask her to give to each kids, most of them know to bring home to their parents.
A lot of parents will not stay anyway unless it is in a far away place and too much driving back and forth. You don't need to talk to them a lot. Just make sure kids have enough to do. Also Buy goodie bags and stuff them with little toys to give to each kids.