Your SO sounds so... negative -- even his first sentence!
If he doesn't "believe" in gifted, you could perhaps go about advocating for the right thing for your dd without using that word. For example, kids don't actually have to go to pre-school. Until fairly recently, most kids didn't. There is actually a fair amount if good research that shows that for kids from an enriched home environment, a little bit of high quality pre-school is neutral, but more is harmful to social development.
When mine was a toddler, I wasn't thinking in terms of gifted. I didn't use that word. But I did really want to homeschool. I just felt in my gut that school would take something away -- maybe because of my own experience. It took a lot of convincing to get DH to give it a try. The public schools here are awful, and the private schools are expensive. He reluctantly agreed to let me try it for kindie, and then after that for one year at a time.
Fast forward six years. DD tested EG/PG on the WISC. Academically, she is doing great. (My husband's area of concern.) For much less $$$ than the local private schools, she is able to take interesting, challenging above level classes through local homeschool resources and on-line through places like Center for Talented Youth.
Socially, she has a wonderful group of really smart interesting friends. These girls are kind and inclusive. My friends with kids in school are worried about what's coming. Already, they see social pressure for certain clothes, dating, and drugs. Social pressure to conform. The kids trash the bathrooms at the bar mitzva's. (My daughter is almost 11.) My daughter went to a birthday party for her friend who is turning 12 yesterday. There were 10 or so kids there, ranging in age from 10 to 13. It was a Mad Hatter's tea party. The kids were all dressed up as characters from Alice in Wonderland. My kid and her friends are "nerds" -- happy, smart, interesting kids who don't need to be mean to other kids to feel good about themselves.
If you look around for info on homeschooling, you will find a lot of stories like these. You may be able to make a strong case for homeschooling without even using the word "gifted," since this is a word that your SO seems to dismiss.
