I also read somewhere that you have a year. At the same time, I read that the stamping is not necessary (*some people argue about it) if you are not travelling before your plastic card arrives. But one needs to go to local USCIS office and fill out form I-89 in order to order card. They take photograph and if you are above 14 year's of age then they take finger print. At the same time they stamp passport if you provide one.
* some people argue that stamp is the ONLY proof that you have a GC and not the plastic card. The counter argument to this is, passport can expire and change so people carry the card. Also, while entering US, POE does not care for whether you have a passport or not. All he asks is plastic card if you claim to be a GC holder.
Gurus, please correct me if I am wrong.
Question to texas02. - How long are you looking to wait before passport stamping? One month, six months or a year? Please share your experience of delayed PP stamping as I may be in the same situation.