Rosie was TERRIFIED when Griffin came home. She didn't want to be anywhere near him. She's been ok with kids at the park big enough to throw frisbees and was ok with Ben (he was 4 or so when we got her), so the incredible stress she had at the arrival of an infant was a shock to us.
I think the key with Rosie was letting her deal with him on her own time and letting her know that she was NOT expected to
do anything or be subjected to anything related to him. If she wanted to be with us she got lovins, if she chose not to that was just fine too- she'd get her lovins later when he was napping or in a stroller or whatever.
I didn't use food really because it seemed to add pressure on her as if she *should* be near him wether she wanted to be or not. She was most relaxed to just have no expectations on her with regards to him. That was just something I observed in HER, so I just went with it and tried to keep her relaxed and happy. Like every baby, Griffin threw a ton of food so he took care of the desensitazation from about 6 months on

You probably saw my posts about her when G was little choosing to sit 10 ft away and pout while Sammy eat all his hand outs. It was pathetic (and hilarious) to see the foodiest dog in the world staying away from food. She never chose to be near him when he sat on the floor and never got within arm's reach with him in his highchair. She avoided him being close enough to touch her when he learned to crawl.
I reinforced her with praise when she took it upon herself to walk away from him when she felt nervous. I swear if there was a bubble above her head it would have said "REALLY? it's really ok for me to walk away from him?" Knowing that seemed to take the weight of the world off of her. She would let out these huge sighs.
The next phase was Rosie seeming relaxed when Griffin touched her when she was right with me but not wanting him around without me. The crawling phase was the hardest because she was still really weirded out by him and of course could move FAST. That was when her "beep beep" and "recall" cue came in handy. That way I could get her out of a place where I thought she might feel cornered really quickly if I thought Griffin could get to her before I could grab him.
I think Rosie got better and better with time but it was when Griffin started walking normally and could throw balls that she decided he was really alright. Now at 16 months, she is happy to let him pet her or feed her without me around. Thankfully G is a gentle, tentative child by nature so it hasn't been difficult to teach him to be gentle and appropriate with the dogs.
Probably a no- brainer to point out, but I think it was really important that Rosie got her usual play time, frisbee hikes etc. Those times really help both my dogs to deal with stress. I was lucky to have family helped me make sure I could give that time to them every day.