The NASA Exoplanet Science Institute (NExSci) expects to issue the first General Observer and Legacy calls for proposals. A date has not been set yet, but will be prior to launch. The GO program will solicit proposals for observing time on SIM, and will be unrestricted in scientific scope and size of request. Many GO-1 observing programs are expected to be in "Snapshot" mode, most of which will require on the order of 10-20 astrometric observations over much less than a five-year duration, typically two years. The Legacy programs will emphasize the scientific "legacy" of the program's scientific results, and their planned dissemination to the astronomical community. Guidelines will be posted on the NExSci website.