My eldest started day care 5 days a week at 10 months as I had to return to work. She was very happy and settled there, and enjoyed going each day - sometimes she would tell me she was too busy to come home at the end of the day. When she was 2 we dropped back to 1 day per week, as I went on maternity leave with my second. She was a little bit more reluctant to go, as it was not quite as familiar to her, but would settle after the first 1/2 hour or so, and enjoy her time there. My 1 year old started a few days ago. I've found it works best if you just say a quick goodbye, with a quick hug and kiss, tell them to enjoy their day and let them know you will be back - and then leave - ignoring any crying or calling for you - as hard as that may be. If they see that by crying or calling for you, you will stay, they will keep doing it, and also as long as you are there they will not be interested in letting the staff settle them. If you are not there, the staff will be able to settle them a lot easier. If you hesitate about leaving, they will see that, and know that you are not comfortable with leaving them there, so they will then think that there is something wrong, and be more unhappy with being left. If they see that you are happy and secure with leaving them, they will feel more secure. If you are concerned, phone after about 1 hour and ask the staff what they are doing - generally they will be playing happily by this time - don't go back or let them see you after you have left, or this will just start the separation all over again.
It can be very hard to do, and I will admit to crying myself on occasion after leaving them - I think the girls get over it quicker than I do.
I hope this helps. Good luck.
mum to 2 girls