Gratuity Calculation From Joining Date Or Date Of Regularization

Employees salaried co operative credit society is having two working staff from 2002. In 2010 as per minutes of AGBM, staff were regularised w.e.f. 2010. From 2002 salary was paid in cash voucher s and voucher details tagged as administrative expenditure. Now provision of gratuity is in under active consideration. So Q1 being ruled by Maharashtra co op society act, gratuity provision is applicable to this society. 2 if gratuity provision is to be made then what should be date of calculation for gratuity.