I was looking around a bit for info on at what age Hebrew school typically begins, and, while practice can vary, especially depending on movement, it appears to usually start with
3rd grade. Assuming that it was always planned for Ephram to become bar mitzvah, it's likely that he was enrolled in Hebrew school around a comparable age.
What this leads me to is a question of why this never comes up, as far as Delia is concerned, until she's already nearly reached the age of bat mitzvah. Unless I'm forgetting a conversation (always possible), shouldn't there have been
some concern about her not being able to begin Hebrew school around the same time -- which would have coincided with S1? Not that the Browns weren't grappling with something huge then, and not that Andy was much of an expert on Judaism, but surely there must have been some talk of this before Julia's death?