No CinemaScore yet (according to BoT they've stopped releasing those Friday night so we won't get that 'til tomorrow), but WOM is off to a pretty good start on PostTrak -
‘Captain Marvel’ Darting To Super $156M-$160M Opening – Midday Update
That 73% "definite recommend" is comparable to
Civil War's 75%, so that might not mean the best legs, though (both BP and IW had "definite recommend"s in the mid-'80's). But...it's better than
Doctor Strange's 67%, so maybe it's not a great way to gauge legs at all, lol.