And to answer your question whales are smart, they will try to get positions in a coin without leaving traces or evidence they are interested in an altcoin, if they left any traces then people will know of their involvement and they will not get their projected profits, so unless you are part of the circle of whales I doubt you will know beforehand in which altcoins they decided to invest.
Most signals will be given once whales or that group already got their coins so that they will get the full benefit. This is just based from my observations and I even tried to ride with it but I lost so it was a lesson learned.