I have always been an advocate of steady buying, at approximately equal dollar amounts (and its very close cousin: dollar cost averaging). I bought a small amount (in BTC) just this week.
So even if BTC price keeps going up, you would buy LESS BTC for about the same $ as last time. Price goes down, you would be more BTC. Slow but steady buying also means that you ARE buying, and that you will not lose out big-time (nor, of course, would you have made massive profits by buying at the bottom). But, NO ONE can adequately predict the future, so slow but steady buying of Bitcoin (as an investment/speculation) makes sense to me.