Ideal time to place an order for any regular cement concrete product is 4-6 weeks, since it involves production planning, concrete curing and finishing, and dispatch planning. However, specific made-to-order products need 2-3 months before the expected date of delivery at site since it involves making of special dyes and moulds, and these are third-party dependent.
Efflorescence is the whitish deposition on a paver's surface, a result of a chemical reaction between moisture in the air and Calcium Oxide present in cement, causing Calcium Hydroxide to be formed on the surface. This Calcium Hydroxide reacts with th Carbon Dioxide in the air forming Calcium Carbonate which appears as a whitish deposition. This is a natural reaction and there is little to nothing a manufacturer can do about it. That being said, there are ways by which it can be removed.
Shade Variation occurs because of small differences in dye lots and raw materials used. The variation becomes a lot less apparent with the passage of time.