The leader of the state’s gambling commission is warning that the casino law contains several unrealistic deadlines that could force regulators to solicit bids for casinos before they have the expertise to judge the billion-dollar projects, or public input on the scope of the developments. Under the law, for instance, the commission could have to seek bids by October. “I can’t imagine that we would be ready by then,’’ said Stephen Crosby, leader of the commission.