Use state initial values in simulaions

I want to be able to use the initial conditions values in my equations, example below. Typically, if we want to describe a change from baseline we also take in a "constant parameter" (placeholder) to "remember" the initial values - but couldn't these values be accessible instead?

d/dt(A) = 1
d/dt(B) = 2*(B(0) - B) + A

A(0) = 0
B(0) = 1