Does a creature tap immediately after regeneration or end of turn? Magic Gathering MTG?

What would the point be in regen'ing twice? Wrap In Vigor regens all of your creatures at the same time. They never really leave the field, all they do is die but never go into the graveyard. When you regen you have to immediately tap them after you declare the regen. Save the second Vigor for a time that you relly need it.