The future perfect is not common - because we do not often feel the need to look back on a situation from a time point in the future. Perfect aspect constructions (present, past and future, progressive and non-progressive) together make up between 5% and 10% of all verb phrases; will and shall very rarely occur with the perfect aspect (Longman Grammar of Spoken and Written English).
The last time I used it was about eight hours ago (really!). Speaking on the phone to a friend, I said "I'm still working on your report, but I'll have finished it by the time you get home this evening." I had indeed finished proofreading his report, and emailed it to him, by the time he got home at six.
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