If you have invented a new product, process or composition of matter, waiting could allow someone else to jump you in line at the patent office and with the new first to file rules at the patent office such a line jumper could get a patent ahead of you . . . and prevent you from receiving a patent for your invention even if you could prove you invented before the line jumper.  Even if no one jumps ahead at the patent office, waiting to pursue protection until after you have sold, offered to sell or otherwise publicly disclosed your invention could foreclose your patent rights in all countries outside the US except for Canada and Australia, which - like the U.S. - have a one year grace period in which to file a patent application after a public disclosure.  Once such a disclosure is made, a one year clock starts ticking in the US and the other grace period countries after which you would be out of luck relative to obtaining patent protection.

If the line jumper doesn't bother to try to patent your invention but instead starts selling or otherwise publicly discloses your invention then this disclosure could also be held as prior art and used against you if you decide to file for a patent application later.  This assumes the line jumper came up with the invention on his own.  If he copied you directly (or derived the invention from you)  then you could utilize the one year grace period to get a patent application on file to retain as much of your rights as possible.  

And if you disclose your invention and don't file a patent application within a year then the grace period is extinguished and your initial disclosure can be used against you if you were to file for a similar invention later.  Also, after this one year period if no application is filed then your invention is fair game for knock off artists and you could find yourself competing against your own product now produced by someone else.

Even if you don't care about your initial invention, this initial disclosure could be important in the event you want to protect the next iteration of your device or product.   If the new version is not new or is obvious (obviousness to be discussed in an upcoming article) relative the old (now publicly disclosed) version then it may be impossible to get a patent, or you may only be able to get a patent on a narrow aspect of the new iteration that separates it from the old version - instead of for your broader invention.    

So this is a call for procrastinators to get moving . . . much could be lost . . . line jumpers await . . .