Bitcoin price trends is upward. It is consistently rising, 2017 is the year for multiple all time high BTC prices and I know it will continue next year.
You can still buy BTC when it fells down a little bit because I don't want to think that it will hit a hard drop. Just feel the market and keep monitoring...
Of course, you should buy bitcoin. I suggest you to buy bitcoin now while the value is still low, and hold it until the value increases then you should sell some of it too. It's just business you know, the cycle must continue.