The video will be released tomorrow as well.
I don't know why they are releasing on a Monday. Didn't their label get the memo?
The song was playlisted by BBC Radio 1, so it's going to have its first play tomorrow by default. Ideally, they should have done like 5 Seconds of Summer or Calvin Harris and Disciples and premiered their track on Friday, so they could have taken into advantage seven days of sale instead of three.