Your dealer sounds mis-informed, or has other plans.
Other dealers have told us that GM should be pulling orders around the end of April, and therefore, dealers should be able to put orders into the system before then in early to mid April. Production is scheduled to begin May 16, and cars should be arriving on dealer lots by June.
If your dealer is misinformed, they need to get up to date on what is going on regarding the Sol. They may also have what they believe to be all of their early allocation dedicated to buyers already, and figure its going to be June before they have unaccounted for orders to fill.