First:
make your decision/opinion about the future of bitcoins.
Second :
Make a personal forecast/estimation for the value of bitcoins in about 1 or 2 years
than conclude:
is your personal value-forecast/estimation >let`s say 2000 €/BTC than ist dosn`t really matter at what Price below 1000 €/BTC you are going to buy BTC.
The higher your personal value-forecast/estimation the less does it matter.
You will be on the winning side either way.
So did I:
Bought and hold
Now I am watching very relaxed and amused price-movements.
The only thing to strictly be applied is:
put only money in BTC you can afford to lose.
IMHO: BTC is
a- once-in -a-life -chance
to participate in a revolutionary changing monetary System[in case this will happen]