Pick up the jr pass and train tickets but use it later on.

Hi, is it ok to pay and book train reservation online, then pick up the jr pass and the train tickets but will not be activate until a few days later? I mean is it possible to pick up the jr pass and train tickets at the Haneda airport on 9/27 but I will not start using it until 10/1 to 10/7 from Tokyo to Osaka? My sister says no. She says that when she pick up the pass they gave her all the reserved train tickets and the pass was activated that day. I am not sure if she is right about it.

Thanks
Lee