{Immediately} (euthe(9373)). This word, common in Mark's
Gospel as euthus, gives trouble if one stresses the time
element. The problem is how much time intervenes between "the
tribulation of those days" and the vivid symbolism of verse  29 .
The use of en tachei in  Re 1:1  should make one pause before
he decides. Here we have a prophetic panorama like that with
foreshortened perspective. The apocalyptic pictures in verse  29 
also call for sobriety of judgment. One may compare Joel's
prophecy as interpreted by Peter in  Ac 21:16-22 . Literalism is
not appropriate in this apocalyptic eschatology.