I think that the most common way to value Bitcoin is like valuing other currency by another currency.
Seeing to it that we all know all the factors that causes or affects supply and demand equilibrium.
Also the time we hold bitcoins. Time is very important factor.
Time and bitcoin, yeah surely they have got the direct proportion relation where bitcoin is growing continuously in its value. Speaking about valuing the bitcoin, well every asset is measured in terms of local currency only and that is just the measure and nothing more. Bitcoin is just another asset and sometimes currency for many users which is valued in terms well dollar. The value it gets comes from the investment that is made into it by big investors, the supply and demand stuff works when the asset is not released from the main server. Too many simple and complex thing that defines the value of bitcoin, with the timeline off curse.