2 Answers

again, all at once, anon, at that instant, at that moment, at that point, at that time, before long, formerly, later, next, on that occasion, soon after, suddenly, thereupon, when, years ago

http://thesaurus.com/browse/then

then
adverb
1 I was living in Cairo then: at that time, in those days; at that point (in time), at that moment, on that occasion.
2 she won the first and then the second game: next, after that, afterward/afterward, subsequently, later.
3 and then there's another problem: in addition, also, besides, as well, additionally, on top of that, over and above that, moreover, furthermore, what's more, to boot; too.
4 well, if that's what he wants, then he should leave: in that case, that being so, it follows that.