You directly say to builder the cheque for balance payment is ready and you will handover the same to him at the time of Registration and get the registration done. Ask him to complete the construction and provide OC , CC, than only full amount is payable legally.
This also depends on the negotiation deal between yourself and builder. If you have promised him to pay 100% before registration then you need to honor him else as per terms and conditions that have been decided between yourselves.
In case the builder defaults and delays the possession of the property as per the ‘agreement of sale’, the buyer has the right to claim the refund of the amount paid along with interest. Even in the case, the promoter’s registration is cancelled, the buyer will have the right to a refund.
You should not done full payment for registration until the work of your flat is complete and builder is ready with Occupancy certificate and completion certificate of the building.
So, It depends on your agreement with builder. It’s always better you make the full payment after receipt of Occupancy Certificate and during possession to builder to avoid delayed possession. If builder refuses to give you the occupancy certificate then you can claim refund with interest and also approach consumer court for compensation.