M.B.
My son passed the school screening even though he has terrible astigmatism in one eye. Both my husband and myself started wearing glasses by 4th or 5th grade so I took him before that to have his eyes tested. He is slightly near sighted in one eye and has astigmatism in the other but he never complained about not being able to see the TV or read a book. Since you have issues, I would start no later than kindergarten and go yearly after that.