This isnt gonna be on itunes until the album is released.
You heard it here first.
I was about to answer about it but guess what? Source disappeared right after I asked at this point I think it has no info left.
Take this with a pinch of salt, I think it'll be up Sunday midnight or Monday morning on iTunes. I think they might not want to waste the promo slots AND it's additional promo. Also, SPS would start gearing up for release week.
Maverick has executed this era so perfectly so far that I have no reason to doubt them at this point. If they choose not to put All In My Head on iTunes, I'm confident they have a reason for it, even if I can't figure out that reason myself.
I don't think the video will be ready by Friday, is too soon.
And I don't know, they will probably release it right before the performance so it goes higher on iTunes with the release effect and promo effect at the same time.
Or maybe this won't be available until Friday with the whole album, idk, if they do that the only reason it would make any sense is that they hope that both AIMH's performances work as promo for the album and not that much for the single, since the song won't be available on iTunes then they are probably hoping more people will pre-order it and maybe since it will already have exposure by the time the album is released it will make more people who won't buy the album buy this song first week and so they will have more SPS for the release week.
Maverick has executed this era so perfectly so far that I have no reason to doubt them at this point. If they choose not to put All In My Head on iTunes, I'm confident they have a reason for it, even if I can't figure out that reason myself.
Mine's a stretch but - could they be readying the video to get huge SPS from the video side? I think the shoot wasn't THAT complicated, could have been done already and a week of editing seems about right. That's the only reason I could think of.
I'd be here for the video dropping this Friday. WFH had the vid release too and THAT showed massive longevity, while the WI video also had consistent runs. They're established streaming forces at this point. My only concern is that the Rhythmic adds date is still a few weeks away - they should push it up already since WFH is starting to drip and drip off the format. But the video would definitely boost sales if released Friday.
Ah... lots to consider!
But yes, stan! 
we are in the same situation dear.
They can drop the video on Friday 
at this point I think it has no info left.