Time expressions

One thing before another
Before I went to work I fed the cat
I had written to her prior to meeting the committee (formal/written style)
It was nice to be in Rome.Previously I had only been to Venice (fairly formal,more informal would be 'Before that,I...' )
I was in the office from 2.30.I was out earlier on. (Before then....-farily informal)
The city is now called Thatcherville.Formely it was grabtown. (used when something has changed its name,state,etc)

Things happened at the same time
While I waited,I read the newspaper. (or more formal:While waiting,I read....; The waiting and reading happen at the same time)
As I was driving to work,I saw an accident. ('As' describes the background when somethings happens in the foreground)
I saw her just as she was turning the corner (exact moment)
During the war,I lived in Dublin. (does not specify how long.)
Throughout the war,food was rationed.(From beginning to end)
She was entering at the very moment I was leaving (this is stronger and more precise than 'as' or 'just as')