Conjunctions: time

When, after, before, until, since, while, once, as and as soon as are subordinating conjunctions which can be used to connect an action or an event to a point in time.

action/event	conjunction	time
She was in a bad car accident	when	she was young.
We can’t play loud music	after	everyone has gone to bed.
Brush your teeth	before	you go to bed!
I’ll wait with you	until	the bus comes.
I’ve been very busy	since	I started my new job.
No one left the cinema	while	the movie was on.
I’ll call you	once	I arrive.
We always have an ice cream	as soon as	we get to the beach.
I bumped into her	as	I came out of the bank.

Many of these time conjunctions can be followed by -ing or -ed forms instead of subject + verb.

When, once, as soon as

We can use when, once, as and as soon as to talk about a specific point in time when something happened or will happen:

When we were in Greece, we went to as many islands as possible.

They always close their curtains once they get home in the evening.

As soon as we hear any news, we’ll call you.

Before, after and until

We use before and after to talk about the order of events in the past or future. With before and after, either the main clause or the subordinate clause can come first:

[event 1]She’ll pick you upbefore[event 2]she comes here.

After[event 1]she comes here, [event 2]she’ll pick you up.

Until as a time conjunction means up to a time in the past or future. In the case of until, the main clause usually comes first:

I’m going to wait until the January sales start to buy a new jacket.

Until he mentioned his name was Doug, I thought he was called Damien! (less common order)

We spell until with one l. (Not: untill)

While

We use while to show that actions or events happen at the same time in the past, present or future:

Can you wait in the car while I run into the shop?

They were talking while the teacher was explaining the activity.

Warning:

We don’t use during instead of while. During is a preposition, not a conjunction, and it must be followed by a noun or a pronoun:

I like to have the radio on while I study.

Not: I like to have the radio on during I study.