Thanks for your reply Ayyash. Do you mean بلا is a more colloquial way of saying تمام ? I’m happy to learn some colloquialisms as well as more formal words, just good to know which is which! When I was living in Morocco, everybody used وها (may be misspelt?) to say ok, but maybe that’s Moroccan dialect?
Tamam means okay, but Yalla is slang and it means "common", "let's go", it never means "ok". And it is slang, although descended from a more formal expression: يا الله: Ya Allah. Which also is part of a longer statement: Bismella: in the name of Allah. So yes, you get up, and you say: Bismella, ya allah, yalla.
Though the moroccan word you said, I never really heard of, it might be true, I live in Jordan, Moroccan dialect is not completely known to me.