Gst registration for branches

Client having GST registration for head office at Mumbai which is migrated from Service Tax registration.

However branches that were providing services in other states were not having S.Tax registration. I presume we need to have state wise GST registration for branches. Any idea, when new registrations will start? Or is there any provision for centralized registration under GST Law as well?

Kindly advice please!

Thanks & Regards,

Valerian Dsouza