When did you introduce cereal/baby food to your baby?

[K's Mommy]

My daughter is almost 18 weeks, and she's back to waking up multiple times a night. By 7 weeks, she was sleeping 5-8 hours at a time, but now I can tell that nursing her before bed isn't enough because sometimes she'll wake up an hour later needing to nurse again. I'm thinking that its time to introduce something to her before bed, but I'm not sure if it's too soon? She was born almost 9 lbs, was 12 lbs at her 9 week appt, and now we think she's about 16 lbs. She's done really well with nursing, and has gained weight just fine. I wanted to nurse her until I could tell it wasn't enough anymore. I think some parents rush to introducing foods. I don't want to do it too soon. When did you start giving your baby something other than formula/breastmilk? And what did you give them first? I gave her some rice cereal in a pumped bottle one night about a week ago, and she slept 6 hours, but I haven't been able to pump any milk. I pumped just now, and got less than an ounce...not enough for a cereal bottle. Any suggestions? Thank you
Lots of great information so far. Like I said, I think a lot of parents rush to giving their baby foods. I don't want to be one of those parents. If she's too young for cereal, then I can deal with getting up throughout the night. Her health is most important. Thank you all so far!!