Please would you advise when I can wear my retainers (invisible) after a facelift and fat grafting?

In my practice you would be permitted to wear your retainers immediately after a facelift. The question should be addressed however to your own surgeon.

Thanks for posting the question.  Assuming there are no incisions inside your mouth from any additional procedures, it would be fine to wear them right even the same day after surgery in my opinion.  Many times patients will ask when they can wear dentures and the answer is the same.  Of course you should ask your surgeon for his instructions.