i don't think it would go back lulu - there may be a way around it but given that the payments will still get made in the installments for an equal period, i don't believe it does.

it sucks that it doesn't go back, but the person doesn't miss out on anything - it just gets paid for 13 installments from now.
ftb and ppp will get back paid - it's just the baby bonus
you can't even change the day you get paid baby bonus to meet budgeting needs - it gets paid when it gets paid... not exactly a well thought out situation