We had a five year old toy poodle when our first daughter was born. He was my everything and I was his.
When we brought the baby home, we laid her down on a blanket and let Dax sniff and lick her all over. Once he did that, he was good. I think the more you try to keep them away from the baby, the more problems you'll have. Where you get into problems is when you stop giving the dogs the attention they are used to - that could cause more jealousy. Of course you won't have AS MUCH time for them but be generous with the time you can give them and that should help.
I've also heard that if you'll bring a blanket home that the baby has been swaddled in at the hospital maybe the day before you actually bring the baby home, then the dogs can sniff it and get used to the baby's scent. Didn't try that but I hear it helps.