I've one or two questions..
How [should or could?] you say this sentence?
Don't speak until I [tell, told, have told or what?] you.
You could write it any of those ways, but if you want it to be grammatically correct, you should write it like this:
Don't speak until I tell you.
Actually, I would probably say, "Don't speak until I tell you to."
What you are meaning is, "I will tell you to speak [later], so don't speak until then." Therefore, you can't use past tense.
If you use "told" or "have told", it would mean you already told them to speak at some point in the past, but still they need to be quiet... until when?
"Don't speak until I told you." (Means: "I told you to speak a minute ago, so don't speak until then." It doesn't make sense.)
Don't speak until I have told you. (Means: "I have told you to speak in the past, so don't speak until then." It doesn't make sense.)
"Don't speak until I tell you."
I think this is the most common way to utter/write the sentence.