I would like to ask about the the words early and earlier if I have this situation( I speak with someone and she expect to receive something from someone before one week from her flight for example)
In this case is it right to say:
The correct way to say this is:
If you don't receive this one week before your flight, then call me.
You shouldn't use past tense, unless you are trying to say:
If you did not receive this one week before your flight, then you should have called me.
I would say:
One week before your flight, if you have not received (the item your friend is waiting for), call me.
I'm not sure I understand what you do mean to say.
The following are more or less synonymous:
One week before your flight
One week earlier than your flight
You don't need both, and in fact it reads very oddly to do so. (You could say earlier, before your flight, but there earlier would mean "at a time before something we have already been talking about", not relating it to the flight, so before your flight in addition makes sense).
As to the difference between early and earlier: in most uses earlier simply means at a time before, as a plain factual statement. Early generally implies a standard: it means something like earlier than expected or earlier than required.
