How to convert absorbance data to velocity?

Lets say each concentration was reacted for 5 mins, using varying 3mL solutions in cuvettes. They were then measured in a spectrophotometer to get the following absorbance data.
0.20mM -> 0.592
0.40mM -> 0.942
0.75mM -> 1.598
1.00mM -> 2.307
1.50mM -> 2.498
 How do i convert them to velocity?
I know i have to use beers law and the extinction coefficient(18,300/M*cm)
But im kinda confused here =/

EDIT: I'm going to take a guess that C=A/3l and then Vo=C/(delta)T which in this case, (delta)T would be equal to 5. Using this info, the absorbance reading, 0.592 measures out to 0.005202mM/min.
Are my equations correct? Do i divide C by (delta)T which is equal to 5?