Hi: I am very close to purchasing an Ipad 4G tablet, but I cannot get a straight answer out of my local discount store...I am mainly interested in using the tablet for the built in GPS chip that I understand is included in the 4G models...(The local clerks don't even know if there is a GPS module in the tablet!)...Do I have to activate the 4G network immediately or at all? Can I activate it at a later date if I choose? Or never? Thanks for the advice!