I'm planning on getting a fraction of a bitcoin. Maybe about 1/4 or 1/8 BTC just to fill my wallet with something. Is now a good time to do so?
Now is not good time to buy bitcoin, lets just earn some bitcoin from signature campaign right now, sell it, and makes price going down. Wait bitcoin under $600, buy it,forget it, and sell it before new year eve 2018 maybe its going to $1100 again

If you want to wait for bitcoin to reach 600 to buy again, I think you are going to wait forever because I don't think we are going to see that price any time soon if ever, so the best strategy is to buy bitcoin when there is a decrease in price but nothing as you suggest.