When to book accommodation?

I am trying to arrange a school trip to Japan in April 2009, but with the poor exchange rate at the moment I want to wait to book our accommodation, in the hope that the exchange rate will improve for us. But, I don't want to wait too long and miss out on bookings. How long before we leave should I make sure I book?

Depends very much on where and what day and how flexible you are in terms of budget. Kyoto during the cherry blossom season can get booked out early in advance, especially on weekends. In many other places, however, making reservations just a few days in advance is often okay.

If you have a school group of more than 10 people, you should make your reservations as early as the hotel/hostel allows. Most places in Japan accept bookings 90 days in advance. At the latest you should reserve at this time. If you cancel within 30 days there is usually no penalty. Under 30 days the penalty varies with the hotel.

If you're a large group, you will be in competition with Japanese school groups who go on class trips in March-May. Places that have enough space to hold these groups can fill up quickly.

My earlier response was written on the probably wrong assumption that you will be traveling in a small group of less than five people.