(every time for present)

If I drink coffee at night

If the sky is without occasional dark clouds

(for future)

If we pick him up ,

(present or future unreal situation)
If I were at home
If I drank a cup of tea

(for past unreal situation)

If I had done this work yesterday

If am hungry

If I were hungry

If I had been hungry yesterday

If I am thirsty in 5 minutes

If they were busy