Hello there! Ed’s signal order for all of his pedalboards since 1992 are covered on his page. Wahs have been a constant part of his setup since 1995, and he’s always them before his distortions and delays (the importance of wahs his setup is discussed in the “starter pedalboard” article).
Placing a wah (or any kind of filter or modulation, for that matter) after distortion or delays will result in a more prominent effect. Trying it yourself is the best way to hear the different. In addition to making the effect more prominent, placing wahs or modulation after delays will cause the sweep of those effects to be heard “on top” of all of the delays – it will sound like a “mastering” effect, such as the filter sweeps often implemented by DJ’s. Placing wahs or modulation before delays will cause segments of their sweep to be repeated by those delays, resulting in a much more “diffuse” sound. This “diffuse” sound is a big part of the texture which Ed creates on live versions of Videotape, as is discussed in detail in this post.