How to install Android to any phone very first time?
The short answer is that it's different for each phone. There's no generic "install Android" procedure for two reasons:


Unlike on a PC, where the Windows installer or Debian installer has drivers to access (almost) any PC hardware, in embedded devices each model needs a ROM image specific to that combination of hardware. The first part of any installation procedure is to download or compile a ROM image for the device you're going to install it on.
The steps to follow to install the ROM are different for each device. Different devices have the internal storage configured and partitioned differently. Some manufacturers may use their own tool in place of fastboot. And of course some hardware might require special measures to access it, such as changing jumpers on the board, or connecting to special pins not normally accessible. Most devices don't need anything so extreme, but even in the easy cases it's important to get all the command parameters correct.


Manufacturers don't have a problem with this because each production line only needs to flash one kind of device. They don't actually have someone sitting there typing fastboot commands over and over again: they use special-purpose hardware and software to flash many devices as quickly as possible. Only those who design the production line or work in the factory know exactly what steps they take to initialize each device.