Actually from my experience from last one year it is very very difficult to predict what is the real time to buy BTC or ETH. It is all out of control i think. If you think you will buy now you can take a risk and luckily you may gainer or loser.
Generally, prices around $7000 is good to enter bitcoin when you have free capital that you don't use. Bitcoin is now in the interval of $6500 and $10000 then it's a good decission to buy some bitcoins from the global exchange markets.