When you trade stocks or you are long-term investor there are a question when to buy? There are a few good answers: divide your capital and buy time to time or buy when price falling by several per cent. But for my opinion best time to by it is look at "smart money" or big participants of market. If they start purchasing do the same. How to identify big participants? It is very easy: they will buy a lot too many. If you have a trading program  which show you volumes, you can identify extra volumes on day charts.

Look at the picture below. It is Goldman Sachs. 24, 27, 28 of June we can see extra volumes on day chart and price grew up. 18 July before Reports Q2. Do you think that's a coincidence? Before reports someone big purchased on big volumes and push price up. And fixed part of profit before Report. Yes these just a game of daddy Cool :)
When you use market profile and volumetric analysis you  see this kind of game!