who long to you have to wait to be able to upgrade early on verizon?

[Marc]

ok i have the moto droid and I wanna get a palm devise but I don't know how long you have to wait to upgrade early like iv only had the droid sence christmas but its heave and clinky but I don't wannna trade it cuz my girlfriend will get mad (she is the one who got me the phone). But like can I upgrade when ever I want cuz the palm pixi plus if free so help me