How many days does it take for spots to appear when a child has been infected with chicken pox?

7-14 days. From time of exposure it is 7-14 days to develop the infection.
Chickenpox. It usually takes 14 to 16 days to get the symptoms of chickenpox after you have been around someone with the virus. Then red spot appear, it usually takes about 1 or 2 days for the spots to go through all its stages. This includes blistering, bursting, drying, and crusting over. New red spots will appear every day for up to 5 to 7 days. After 10 days, your child can go back to school.
Varies. From exposure to spots is variable from 10-21 days, average 14.Exposure can occur up to 24 hrs before someone breaks out & as little as 30 min in the same room as an infected person is adequate to transfer the germ. Since most kids are now immunized as infants, most are immune.

Related Questions

I have varying stages of chicken pox all over my face, around 200.Can I wash face w/ mild soap & water? Or leave it alone so as not to infect d spots?

Yes. Washing is fine as long as the soap does not irritate.
Chicken pox. It is best to let the chicken pox scabs fall off on their own because of the possibility of forming scars when using soap and water on the lesions.