Whenever the market of altcoins is found to be at the bottom make some investment. The altcoins invested should be chosen perfectly, if not we will be in a situation to hold for much longer time period. With altcoins we also need luck, at times what we've chosen to invest won't pump and the rest spikes.
deciding which altcoins to buy and invest for any given time is the tough one. sometimes we just buy altcoins based on marketcap ratings and altcoin popularity.
we might forget about altcoins with roadmaps that are already close to a big event. back during the ICO season, we could see tokens that had renewal often get a good pump in the market. but maybe the current situation is different. focus on investing in altcoins with good popularity and reputation.