When is a good time to buy?

I have no answer to my own question but i might be able to predict the period of dropping using graphs.

Let's look at 2 stocks that i might want to buy and based on a 5 year average determine the period to purchase the stock.

Color code indications:
Red - Aug-Sep
Black - Feb-Mar


HK Land

Source: Bloomberg

SATS

Source: Bloomberg

However, it does not always happen for all the stocks. It just happened that these 2 stocks show slight similarity in their drop periods.

Both stocks showed that their major drop in share prices happened between August to September.
It would be good now to wait till February to see if the tapering announcement in January really kicks in or will the Fed continue on their monthly bond purchases and keeping interest rates low.