According to the national regulations, the company must pay social insurance from the first day of work, so the insurance must be paid from the first day of employment. As for salary, you have established a factual labor relationship with the company, and you have not signed a labor contract, so you need to pay double salary.

When you go to arbitration, you can ask for dual employees and social insurance (including pension insurance, medical insurance, unemployment insurance, maternity insurance and work injury insurance), but you need to provide the arbitration department with evidence of actual labor, such as your attendance and your effective payroll, or the company will make a big fuss about labor relations for a long time without you providing evidence.