Milo hasn't started yet (but will this week), but my girlfriends daughter went to creche at 11 months, alternating 4 days one week, 3 days the next.

After the initial period of crying when they got there etc had passed, she loves it. When they're getting ready for work, she has her bag packed and waits at the door, sometimes rather impatiently, wanting to go.

I think a lot has to do with the care that your chuild is getting, so as long as you're happy with the care that you have chosen it should be fine.