The answer depends on a lot of factors... your child's personality, her level of giftedness, how the staff accommodates her, and how the school screens for giftedness, just off the top of my head.
Generally speaking, those two first years in a regular classroom have a strong capacity for making gifted kids miserable, and turning them off of learning. This forum is littered with horror stories. The best solution appears to be homeschooling, but your results may vary. Some parents have reported success with Montessori private schools. With the right staff in place, publics seem to do better as a whole than traditional privates, because they have more resources... but usually, both fail these kids miserably.
Regardless of how the next couple of years play out, if your child is gifted enough, and she goes into testing with the right attitude, then there's pretty much nothing short of massive head trauma that can stop her from qualifying for that gifted program.
