The eligibility criteria for a shop & establishment vary from 20 to 10 employees from state to state, where the notification under section 1(5) of the ESI Act is provided for a particular state. First, clarify whether your company falls under a Factory or establishment.
In the case of an establishment, if ESI reduces the number of persons required for coverage from 20 to 10 in your state as per the Gazette, then your unit will be covered. Otherwise, you have to wait until you reach 20.