I.G.
Your school district is Northshore, their preschool is at the Sorensen Early Childhood Center. You have to call them to figure our eligibility. Here in Shoreline Children must be 3 on or before September 1.
Good luck.
Edited to add:this is just the public school preschool, private preschools are a lot more flexible regarding age but they also tend to be pricier. And yes, if your child misses the cut off date most school districts will require you to wait a year.
I would strongly suggest that you contact your school district. You seem to have a lot of questions and it will probably help you getting them answered in person.