Often I hear the follow said (or similar variations):
So if I don't see you till then, have a nice vacation.
Now I suppose that the intent is that if I don't see you until you leave, then I'll wish you now with have a nice vacation.
However, to me the sentence seems flawed if you take it at face value, in that it could sound like the wish have a nice vacation is only being given on the condition that I don't see you till then.
So I'm wondering if
the given form of the sentence is in fact okay (and not flawed) and
Is there an alternative succinct way of saying the same thing?