Ich würde gerne die Bedeutung verstehen:
Dann hast du wohl keine Zeit.
Was bedeutet hier wohl?
The number one function of "wohl" is to express an assumption.
This means something like..
Just like "to guess" and "to suppose" the person who is saying that can very well be very sure about the other person's not having time, so the assumption is just used to distinguish it from a statement.
That sounds as if I am telling that to the other person... like...
"wohl" has some other meanings too and emphasis actually plays a big role but more on that as well as more examples can be found in this article on my blog.
it can be used always to make something sound less resolute, e. g. to be more polite or if something is not certain, assumptions, etc
Also it is used for pointing out something that turned out to be false, like a false assumption. Its not a provoking statement, but its not neutral though.
Bedeutungen:  wahrscheinlich, vermutlich  veraltend: gut
The bold one is the one applicable here.
You can say "Dann hast Du wohl keine Zeit". This would typically be used in the sense of
A: Gehst Du heute Abend mit mir ins Kino?
B: Nun, ich muss meine Mutter anrufen, meine Steuererklärung machen, und meine Wohnung putzen.
A: Dann hast Du wohl keine Zeit.
I deliberately chose excuses that one wouldn't prefer to going to the cinema, normally. When Speaker A says "Du hast wohl keine Zeit", he expresses disappointment, and a certain disbelief in Speaker B's excuses. I don't know what the origin of "wohl" is, in this case, it's just how i would use the word.