First, I have nothing against e-collars. My biggest concern is will your dog associate the correction from the collar with the dog instead of the behavior. There are many different thoughts on this.
I do know that with Woolf, if my timing was bad, I missed his signals and didn't redirect, he wouldn't learn anything from a correction once he is reacting. He doesn't get a correction for reacting to dogs. Instead I get him out of the situation, then begin again. I have messed up at times and corrected late and his behavior escalated. We would lose ground and had to do some extra work to regain it.