3.  Time clauses are sub-clauses introduced by one of the following conjunctions : when, while, as soon as, after, before, until  They refer to the future time but they are not usually followed by a future form. Instead, we use a present simple.

4.  As soon as I get home, I’ll have a shower.  When I graduate, I’ll give a party / I’m going to give party.  I’ll stay there until you arrive.  Before I leave, I’ll close the door.  After I have worked, I’ll have a decent meal.  Will you feed the cat while we’re away?

5.  Time clause : present tense (present simple, in exceptional cases present perfect) As soon as I get home, …  Main clause : future tense (will + infinitive, sometimes the going to-form) …, I’ll have a shower.

6. Sentences with a time clause have the same structure as the first conditionals. However, ‘when’ and ‘if’ have a different meaning. Compare : I’ll give it to John when I see him. (It is certain that I’ll see John.) I’ll give it to John if I see him. (if = in case) When I’m in London, I’m going to buy a sweater. (I’m going to London in the near future) If I’m in London, I’ll go shopping. (I may go to London but this is not certain yet).