We were lucky as the nursery opened and Bob was the first attendee. That means he has always been the king of the castle, and didn't have to get used to 20 kids at once. First it was just him, and then him and another kid and then 3 and so on.
He's been going a year now - and he loves going, he waits by the garage door with his basket.
I orginally put him in so I could decide what I wanted to do work wise, so he just went 10 hours per week. Now it's going to be around 19 hours this year, but he does have 2 whole days were he doesn't go. He has never cried, or not wanted to go.
I would say put him in when the stakes are low - ie you haven't got a job. It will free you up to have your hair done, go to interviews etc. and will mean you will have lots of time to settle him in.
My tip is to let him choose something to play with and play with him for 5 mins. During this time a member of staff should gradually take over. When he is absorbed with them, say you are going, but will be back after (afternoon tea, lunch, storytime - whatever).
A year on we still say "daddy is picking you up in the blue car".