i went on the pill around the same time i started working out more seriously, and i've seen nothing but great results...
everyone is different, you'll probably just have to judge your own tolerance and sides, but i'm tempted to say that it shouldn't matter, as long as you are in the gym, pushing weights and challanging your muscles..
most gals who are among the 'elite' may have opted out of the pill at some point in their lives, but most do this b/c of the fat gain... i've personally never heard muscle loss as a reason (or have seen it listed as a side effect of bc)