On average it takes about six weeks for a child to settle into care. By leaving him three days a week, you (and he) will find it easier then a child who only attends one day a week. Would mornings be better to leave him (if possible) he may be happier (or not so tired) then. He may also be fine for a week or two then regress before settling easier again.

I'm a family day carer, and have had a new little one start at the end of Jan. Only this week he came in without tears. The last few weeks he has been crying when mum gets him out of the car. He didn't cry when his mum left, but when the next mum left. This little guy is now 18 months old and in care 2 days/week, so yes it can happen.