it's better to buy at the bigger dips and hold, wait until it pumps up again this might work if you're thinking for long term investments but if you're after in short or you buy at the high price then it dumps and try to sell then because you're afraid that it's a loss then probably it's a dumbass idea. if you're planning investing in short term then you should be prepared about the outcomes since it's risky and you should invest what you can afford to lose.
Yesterday there was a drop as you said. So it is a good time to buy bitcoins. I suggest not waiting for the price to pump up because the profit isn't big yet and you should keep holding the bitcoins until they touch the last ATH price. That would give him a huge advantage.