How much time does it take to analyze the original and copy it, set up for mass production, advertise, etc? Then, how much time until demand shifts from the ori

How much time does it take to analyze the original and copy it, set up for mass production, advertise, etc? Then, how much time until demand shifts from the original to the generic in each market (India, US, etc)? According to the OP the company was making "billions every quarter" on sales in the US. Considering the research often costs "billions", they should make a profit in the first quarter by selling in multiple markets if it takes around a month until the demand shifts to the generic.