Daughter with sitter for the first time

I'm able to take my child to work with me but after I have my second child (due November 10th) I won't be able to bring both of them so I'm planning on taking the new born in hopes of having a more successful time breastfeeding. Because of that my 2 year old will have to be in day care full time. To try and make the adjustment as easy as possible on her we have decided to start her out with just a couple days a week until then. Today is her first day and she had no problems kissing me goodbye and was happy when I left but I'm a mess. I miss her so much and all I can think about is if she's OK or if she's missing me. Any other moms have any advice for sending your child to a sitter for the first time?