This has been a contentious issue for a long-time.
As per the ESI / EPF Acts, It is the statutory responsibility for the employers to register their establishment/factory once they reach the required strength of 10/20 employees. Moreover the Act doesn't include and provisos for ifs & buts here. Therefore the authorities insists that even if you do not have any employee eligible for coverage, your company stands to be covered since it is is eligible for coverage.
Moreover, for EPF you need to pay only Rs. 7/- per month to maintain your account, in case you don't have any individual employee coming under its coverage. In case of ESI, you need not even pay that amount, simply submit a " NIL " Return every half year, until you employ any coverable employee.
Regards
RAmesh