Good time to invest is when market is down. If you invest when market recovers and prices go up you may experience dump and then you won't be able to sell it and make profit.
Don't wait too long you might miss the train.
It is true that if we make an investment when the market falls we have a big chance to get bigger profits just by holding a coin until the price goes up, but if we are more careful there is nothing wrong if we invest when the price rises at the beginning of the point because the market will show increase.