GST Registration

u can strt the business operation from 1st day of registration.

If business is getting zero operation than you have to file nil gst return.

or u can cancel this as your own voluntray

when u r registered person opting composition levy.then here u have to start business operations within 6 months of the effective date of registration.However,if u r falling under regular scheme of Gst, then no necessary requirement to get start business operations... as there is no prescribed period of it. In that case u can file nil return for nil business operations as u r registered person and accordingly bound by the provision of gst, that require tax period return filing
so as per ur case if u r in composition scheme, then start business within 6 month as said above, otherwise in regular scheme no mandatory to start operations

also in case of voluntary registration if u don't start business in 6 months of registration ur registration is cancelled