R..
I did something similar... NOT on the advice of my pediatrician, but because I wanted to encourage the pacifier instead of finger/thumb sucking. (Pedi. did say it was OK to do though) Babies usually suck their fingers until they 'discover' their thumbs... I figured that it will be MUCH easier to break the pacifier habit than thumb-sucking later on in life. So if she was sucking her fingers, I would replace with a paci. Although, I usually let her fuss and soothe herself. The only time I gave her the paci was when she wanted to suck on her hands.
I figure this is one of those instances where the pedi. gave personal parenting advise rather than medical fact. There is no 'right' vs. 'wrong' here... it's simply 'thumb (fingers)' vs. 'paci.' It's kind of like how one doctor might tell you to CIO while another might reccomend going to a crying baby.
My DD isn't really a sucker now though... at 11 months, she only takes the paci. when she's sleeping.