Invitation mail : real entry date and theoric entry date

One little question about invitation mail, whatever it's about airport entry or land frontier entry : is this a problem if the real entry date happens several days after the first day of the period mentionned in the invitation mail ? I think the answer is no, logically...
Thanks in advance :-)

Are you asking is it ok to enter after the date on your approval letter?

If it is, then the answer is yes.

Yes, by "invitation mail", I meant "approval letter" ("lettre d'invitation" in french language). Thanls a lot :-)

New topic