There are 2 ways you could do it.
1/ Buy a bottle that was bottled on or near the date of birth, but you may find it impossible to find, as a bottle sold today could have been bottled 2 years ago and distilled at least 3 years before that. Not many whiskies show the bottling date.
2/ You could buy a bottle in 21years time that was distilled near the date of birth.
Any bottle bought now will not have aged any further in 21 years.