My friends would change the diaper once they realized that the diaper is wet or whenever their little ones have a bowel movement. I think getting a good pampers is important if you are not changing that frequently.
Here is a blog post that you may find useful, I think the review is quite comprehensive:
http://www.jashuat.com/the-poop-diary-diaper-brands-review-and-caring-for-your-babys-butt/
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