Only if you are resolved to flushing at all. Flushing seems great in theory until you really think about it. It's not going to take any "chemicals" out of the plant. The salts from the nutrients are a part of the cell structure and they arent going anywhere. The idea of flushing also isn't supported by science. Look into it, make your own decisions, but after exhaustive research I changed my opinion and decided flushing probably wasn't the way to go.
Again, if you're flushing no matter what, yes, now is probably a good time to start.