I agree with
BadPinkTink that you
might be able to do both, but it'll be tight on time. According to
Disneyland.com, WoC - Season of Light has a run time of 23 minutes. That will give you about 20 minutes to get out of the WoC viewing area, get into Disneyland, and find a fireworks viewing spot. I think you're most likely to be somewhere on BVS or in the Esplanade when fireworks begin (that's where I was the last time I watched WoC, but we didn't try to get of the viewing area as soon as the show ended - we let the crowds thin a bit because we had a stroller to deal with).