IGST or CGST/SGST

1) First of all you must take registration in gurgaon because you have warehouse in gurgaon

    Aggregate turnover means all india PAN based turnover (if your one unit is registered and others are unregistered ,you must take registration for all other units irrespective of the fact that other units turnover is below 20 lakhs)

2) if you transfer goods to warehouse in gurgaon you shall issue tax invoice or when warehouse unit transfer goods to you in delhi they issue tax invoice(Interstate goods transfer is not possible withoit separate registartion)

3) when units are in same state disclose as additional place but in case of interstate separate registration is required.   

4) once you have taken separate registration issue tax invoice and charge CGST and  SGST

  location of supplier -gurgaon

  place of supply -gurgaon