Have you heard about this term bottom fishing? When do you think it would be best time for retail investors to know when to enter the market nearer the end?

What you are referring to I believe is similar to Sir John Templeton's way of finding bargain stocks at the "point of maximum pessimism'. While it is possible to bottom fish, it is not within human nature to actually time the market because of emotions. Cheap may get cheaper and over time fear prevents us from actually investing when market is fearful. I would recommend you to split your warchest into tranches and invest either passively through an index fund/ETF or averaging down into the market. That way you are ensuring that you are getting the discount while also having peace of mind. Statistically speaking it is almost impossible to time the bottom of the market. Cheers

Market timing is not possible at all