Okay.....to the best of my knowledge, and having the history of being down in WDW for several parade taping weekends...
Friday is not normally part of the actual 'parade' taping. Yes, there will be tapings going on, but they will be in front of the Castle for the most part. Been there, been part of those tapings several times. I've been in MK on Sat afternoon, after the actual parade taping was done. Won't ever do that again...talk about nightmarish crowds.
But, on Friday?? It just isn't a big deal. And I just can't see Disney taping the actual parade on two different days...they can't do that with the various acts and talent they have coming in. Yes, Sunday is a rain date...but it's not as if they finish up taping on a second day..it's all pretty much 'all or nothing'. So, go on Friday...it will be fine.