The seams of a new tent often leak the first time they are subjected to moisture.  It will take a few exposures/soakings to shrink the needle holes tightly against the thread.  To minimize this possible leakage, we advise customers set up new tents and soak the seams with a hose several times, allowing the tent to dry thoroughly between soakings.  If this procedure is not practical for your situation, we then suggest that you arrange your tent so nothing sits under the seam that may be a problem if it gets wet.  If your tent leaks at a few spots along the seam, you may rub wax or a bar of Ivory soap to fill the stitch holes.  If you apply waterproofing, do so only in the places where it leaks and do not cover the entire tent.  When an old tent starts leaking in the middle of the fabric, far from the seams, it is time to buy a new tent.