Not actually a question - it's a link to a recent blog post that describes a procedure for working it out. Hope it's of interest:
https://jeffollerton.wordpress.com/2015/05/10/how-does-a-scientists-h-index-change-over-time/
https://jeffollerton.wordpress.com/2015/05/10/how-does-a-scientists-h-index-change-over-time/