Is it possible to calculate the private key if you know the time (in the suitable format) when the key was generated on a single PC (Windows, Linux or others)?
P.S. Using it's custom libraries for this magic.
No, the time when the key was generated is entirely irrelevant. A private key is essentially a random number and with a robust source of randomness the time it takes to generate this random number is completely independent of the random number generated. For example, if we both run the same random number generator for exactly 5 minutes we should each generate completely different random numbers. With a flawed source of randomness we may both generate the same random number after exactly 5 minutes but this source of randomness should not be used for generating private keys.