It is supposed to mean "nearly" or "not quite", but alot of
people would use it too mean "20+ mor minutes". in other
words, "almost" can sometimes indicate a delay in a certain
action.
"I'm almost finished
cutting this man's hair, you're next!!"
20 minutes later:
"
Dude, you told me 20 minutes earlier that you was almost done
cutting this man's hair! WTF!!??!!!"
"sorry. I'm done now"