It'll be weird seeing Infinity War doing less than Black Panther.
Indeed it will. It happened to Justice League couple of months ago, where it did less than Wonder Woman.
November also seems like a wild card month anyways in terms of box office performances. Even some blockbusters that otherwise felt more like summer releases in November, like superhero films, would be taking quite a risk every time. In JL's case, both wom and having a large budget also didn't help it out much in its favor.