@raghup I agree, this is poor advice.
It sounds good at face value, but leads to selling when it's down, and buying after it goes back up!
Buy early, buy during growth of a product or industry, buy more when it's down if you believe, and always be looking for the next thing to invest in, early!
Don't get caught up in the drama, and put it away for a year or two, and see how you do!