How much time does it takes to build an 70,000 sq.ft in India?

In the question itself doesn’t say what kind of construction wanted to be done. 

Now let me assume it is a warehouse. If the site available is clear from any type of hindrances, if material is available, there is no crisis of fund and adequate labour supply is planned well in advance, then it will be completed in 16 to 18 months positively. All the decisions during the time of construction should be given at site in advance so that no activity is hampered. So in ideal condition, it will take 16 to 18 months otherwise it may take a minimum of two years in normal circumstances.

If it is a multi storey building of G+ 4, then it will take minimum 18 months to 24 months. Before that, it is not possible. Again it is assumed that it is a simple RCC construction and toilets fittings extra, choice of tiles etc all are given and made available before start of the work.

But I will not be astonished that full completion of the building may take more than 2 years but less than 3 years. Because in India, we have a rainy season, we have extreme cold season, we have Durga Puja vacation, we have Eid,we have dipawali and being agricultural country we have crop harvesting season as well. So every year, we have to stop the work for at least 45 days minimum due to labour supply problem. I am not talking about natural calamity like draught and flood.