I'm jumping in here REALLY late but I hope you have found what you want Jenn. Both my girls are born in Nov. so we have had to start them late. It was okay for Signe because I didn't start her early in preschool so she only had two years of it like normal kids and didn't get bored. But Zoe will be having three years of it before Kindergarten but she's also a special case because she is in Developmental preschool and gets speech therapy every day.
I was also a child who started late in school. (Born in Oct.) And I think it had an impact on how I viewed it socially in my school years. Some of it was good and some of it was not so good. I can't say as to how it impacted my academic skills. That would be one for the professionals.
I guess since I don't have to worry about when to send my kids to school, I can't really help you decide what to do. I've read what everyone says and they all make good points. I guess you're just going to have to trust your instinct and do what you think is best for Mason in the end.
Good luck Sweetie.

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