The time for a

capactior in a

circuit to:

A.) charge to (1-e

^{-1}) % of the difference between current charge and the maximum charge. (63%)

B.) discharge to e

^{-1} % of the current charge. (37%)

As a general "

rule of thumb", a capacitor can be considerd fully charged/discharged after 5 time constants.
The formula for a capacitor's time constant is:

t = RC

Where R is the

resistance of a circuit, and C is the

capacitance of the capacitor.