Revenue recognition on the sales of houses when payment is instalmental

A real estate company is into construction and sales of low cost houses, where the houses will be advertised for subscription even before the construction work starts. how should revenue be recognized if;

1. the subscriber money is used to build their houses
2. the company obtain a loan from bank to build the houses
3. the company get a housing loan on behalf of subscribers

and at what point can we say the houses will be transferred to the buyers?