I'm with Master of None. My DD was able to enter first grade early at our public school after completing full-day private K. Private school wanted her to repeat K because of her age, but the public school offered early entrance. They agreed with me that she would be bored out of her mind repeating K. Although she is not always as challenged as she should be, I offer as many supplementary opportunities as I can, especially in math and science, her two strongest areas, to keep her engaged.
We had to make some adjustments recently. She and two other early entrants are in 6th grade gifted cluster and all three skipped 6th grade math and are in 7th grade advanced math in the middle school. This has worked well for us. The school's faculty and staff are very supportive though the district administration and county paperwork and testing were a bureaucratic chore. Check out your State Board of Education policies on early entrance to first grade and see what the public schools can offer in terms of meeting your DS's needs before you make a decision to repeat K.
