Confused about buying a flat in gram panchayat area

We have given 4.5 lakhs initially to builder for a flat in Ganraj Villa, phase 3, nandivali panchanand, dombivli east priced 23 lakhs on 23-Nov-2021. However since then the registration for gram panchayat flat is not open. As we have applied for home loan of 14 lakhs, the builder is asking to pay remaining 4.5 lakhs and once the registration starts the remaining amount will be paid to him. We are asking for notary for paying the pending 4.5 lakhs, but the builder is like 'I will only mention that 9 lakhs is paid to me and not the actual amount of flat will be mentioned'. We are curious of whether the gram panchayat flat registration will ever start or not or is it good to go ahead with buying the flat.