Grammar

Hi!
I need help with this sentence.
明日にならないと開きませんよ。
I don't get the にならないと part.
I meant it to me "The store doesn't open until tomorrow.", but my Japanese friend corrected it. She's a native speaker.
And the "store" part of the sentence was mentioned earlier in the conversation so it's not in this one.
Thanks! ^^

Aないと、Bない means "not B, until A".

明日にならないと開きません
(The store) doesn't open until tomorrow comes.