There is no legal right to an advance--the law does not guaranty you the right to get one. You can speak with the other side's attorneys: maybe they will expedite matters. There are also firms that will basically purchase your right to compensation and pay you more quickly: e.g. if you get $50k, they may give you $30k immediately, but then they get the $50k months or years later, when the money is paid. You can speak to such firms and see if any can help you, but be aware that you will give up (typically) a lot of money by doing this.