You can get a partition deed executed among yourselves.
A partition deed is a legal document used in property law to formalize the division of jointly-owned property among co-owners.
The partition deed needs to be registered and stamped.
The partition deed should specify each person's shares in the property.
Before that you all execute a joint purchase agreement among yourselves stating that you all intend to buy the property but the registration to be done on one single person which can be divided among yourselves at a later date.
This backdated deed can be prepared in advance so that this becomes an evidence for the investment made by all others which will then enable you to get the partition deed executed and registered accordingly