JR pass and reservations

Planning to use a JR pass to travel Tokyo/Takayama/Kurashiki/Kyoto in early/mid August, with end of trip occuring during Obon. We arrive in Tokyo August 2, start travel August 7. Based on previous correspondence on this forum and other research I have found that it is impossible to make train/seat reservations in advance from outside of japan, at least not without huge additional expense. So our current plan was to make all seat reservations immediately on arrival August 2, for start of travel August 7. However, information I have seen elsewhere suggests that you cannot make seat reservations for JR travel until you actually activate the pass (i.e. turn in your voucher), and since we don't plan to start using the pass until the 7th, that would mean that advance reservations are impossible. Is my understanding correct? Advice, anyone? We (3 of us) are not eager to travel without reservations at this time of year ...

It is correct that you cannot make free reservations until you have exchanged your voucher into the actual pass. But note that you can turn your voucher into the actual pass as soon as you arrive in Japan!