you could do it inbetween meals like you would a snack. And if she's really hungry then she probably wants what is familiar to her.
you could add just a little cereal to her bottle so that it thickens a little and starts getting her used to the thicker texture.
Also, our dr. and several books I've read says that when you start baby food you should start with the greens first. They are the highest in fiber and least amounts of "sugars". If you start with carrots or sweet potatoes first, then go to the greens they may not eat the greens as all because they've acquired the taste for the "better tasting veggies".
and don't do fruits b3 any veggies. Yes, those are the great ones, but even if you had to choose whether to eat green beans or peaches...you'd probably go for the peaches by the fingerful.
Some babies will never have cereal. She could be just fine on formula until 6 mos. If the bottle isn't giving her enough then supplement after she's finished the bottle. Once she's done drinking the bottle she should relinquish it easily and take a few bites for you, unless she's been allowed to use the bottle as a pacifier and have it at beck and call. if you're sure to only have the bottle out for eating, then she won't squall for it as much. My kids never used a pacifier and never cried between.