Wiseduck

I've been having serious issues with a friend's Nu (no surprise right?). During her driver-blade combo from the ground (DD-->4DD-->236D) I finally managed to get the timing down to where I can sledge B during it to try and close the gap. Unfortunately all he does when he sees the sledge start up is dash in for a 3C. Just when I finally thought I had something on Nu it was taken away! Any ideas on how to improve this? or completely forget Sledge B during that combo?