It's always a good idea to come up with a strategy for when you're going to buy (and potentially sell) coins rather than just continously aiming to buy a lower price (you're more likely to sell at a loss then too imo).
Few people buy bitcoin at the bottom and most of them either buy randomly or buy without having specific strategies. The market will never tell you were the bottom or top is accurately and it only shows you area of conference and at that waiting to buy at the lowest of the lowest will always cost you to lose investment opportunities.