Yes, then can do it and back date it too. Just hand in notice assuming she is not confirm and see what is their next move.

Anytime before the confirmation, the terms in the letter of offer continues to be effective until such time a new offer supersedes the existing letter of offer. Naturally this is the case when a person is duly accepted by the Company.

To put it simply, if you don’t confirm me after the 3 months, the existing terms will continue to apply.

Say for example, if the Company does not confirm you for a period of 7 years, which terms continue to apply? Logically it is the existing terms contained in the letter of offer will still continue to apply. Since, there are no other offers that supersede the existing letter of offer,

Next question, once your friend tenders her resignation, suddenly management decides to pop out with a confirmation letter.

Regardless, whether it is dated the same day, back dated or whatever date for that matter, the pertinent question is still the following:

1. when did you have knowledge of the confirmation; and

2. when did you receive the confirmation (as in actual receipt).

So long as your friend does not sign or do anything to verify the contents of the confirmation, the existing letter of offer (signed during the probation period will continue to be effective).

My advise if they do date the LO after your probation period or back dated the letter, just write back and inform they that you will consider their offer and also informing them the date you "ACTUALLY" received the confirmation.