Since there is k-12 in the Ph, on what age should our little ones go to school? I have a 3 yr btw, turning 4 on September.

Depends also on the cut-off birth month (depends when the school's term starts). Best to check with the school you're eyeing. But I think 3-4yo is a good age to start since the immune system can already sort of handle all those preschool germs!

6 or 7