A well built camping tent is designed to be used right away without having to water proof the seams. If after a few years of hard use you notice water coming through a seam, I suggest spot sealing with Seam grip by McNett.  Upon rare occasions it might be necessary to reseal all seams in a tent.

You should always store your tent in a dry temperature controlled area. Don’t store your tent in the garage or attic as they have a wide range in temperatures and humidity. It is also a good idea to roll your tent out every few months to prevent mold. There isn’t any need to pitch the tent.