I just asked my vet about this yesterday. He told me that if they don't lose the milk teeth by 7-8 months, they're not going to lose them. Yoshi is finicky & I thought that perhaps the extra teeth were making it uncomfortable for him to chew. I was also concerned about his jaw getting overcrowded. Yoshi is 7 months old. My vet says that waiting 5 months to extract the baby teeth won't hurt his jaw.
I know that doesn't exactly answer your question. But if you're planning on getting her spayed earlier than one year old, maybe you could give it a month or so to make sure that all of the sharp baby teeth are going to come out, do in fact come out.
I wiggle Yoshi's every night when I brush his teeth just to see if they're loosening up any.
And just for the record...Yoshi's extra teeth aren't making it hard for him to chew. He's finicky because I spoiled him.
