This is not your dilemma alone.
Many traders and investor worry about the bottom of the market and try to do bottom fishing. They wonder when to enter. Their anxiety stems from the fact that the market can fall further. They wonder about the right time is to enter the market.
To answer your query, i would say that every correction is a great time to buy if you are an investor. As a buyer, you should be happy getting a stock at a cheaper rate. For instance, if HDFC Bank made a high of 2200 and if you can buy it at 1900, you should take the opportunity at the moment.
What if it falls further?
Well, buy again.
The golden rule of the market is always sit on cash. Not all of it because then you will lose the opportunity. But you should sit on some cash. You should buy in small quantities. If you have the funds the buy 100 HDFC Bank, buy 20 at the moment. Buy more if it falls further.
As a trader, you should follow a different rule. You should buy near a support. For instance, if you think 10000 is a strong support for Nifty. Buy your favourite stock around 10000 sort of levels. The same applies to stocks. For instance, if 1900 is a strong support for HDFC Bank, buy around those levels and sell around 2200 which is the high. Only difference as a trader is that if the trade goes against you, you need to use the stop loss. So keep a stop loss of 1850 and get out if it goes below 1850.
On the other hand, you will profit if it respects the support and goes up.
So whenever there's a correction, the right time to buy will depend on whether you are an investor or a trader. For both, the rules are different and you should follow them in order to avoid burning your fingers!
Wish you happy trading!