Yes, your daughter will be able to visit the JR ticket office and a JR station and make seat reservations on your behalf (There may be a small charge associated with this). Alternatively, she can make seat reservations for free at [eki-net.com] online (website is in Japanese).
For departure on the 25th of April you have lots of time for your order to arrive should you place your order online. We use FedEx for all our orders who offer a very prompt and efficient service and you can find all our delivery speeds on our delivery page online. Please note that we require 1 working day to process your order before we dispatch it.
Hope this helps!