1. We use ‘since’ in front of a finished point in time in the past. Example: since June / since 10:30/ since last Tuesday
2. We normally use ‘since’ with the present perfect to describe an action or situation that began in the past and continues in the present. Example: We’ve been married since 1997.
3. We use ‘for’ with a period of time. Example: for two years / for eight hours
4. We can also use ‘for’ with the present perfect to describe an action that started in the past and continues in the present. Example: We’ve been married for 22 years.