Why do you think that John puts "after" at?
"And after that I looked.."
"And the seven angels came.."
Why is it that some people try to shove "after" sections into previous parts?
Let Rev. 15:4 bring one section of prophecy to an end. Start "after" that a whole new story.
So in Rev. 15 we have...
one story of John saw the seven last plagues
with "seven angels"
after that story
he saw - the temple opened in heaven
and out came the seven angels
John now gets a new story that leads up to how they eventually ended up with the vials.
"And the seven angels came out of the temple, having the seven plagues..."
"And one of the four beasts gave unto the seven angels seven golden vials full..."
/So the angel group now has
seven that they came from the temple bearing
and seven that one of the four beasts gave them
"And the temple was filled with smoke....no man was able to enter...till the seven plagues of the seven angels were fulfilled.'
till all plagues are over?
Till the ones the angel group came from the temple with before they were given seven more.
the seven plagues
then received seven last plagues