standby database PIT recovery

Hi,

We are planning to implement Physical standby database(DataGuard) for disaster recovery/human error protection. I understand that we have option to DELAY log apply on standby site. We want to recover from human/application error with 4 hour notice time. So we can setup DELAY parameter for 4 hours. But I couldn't find any document about switching over to standby with Point In Time option. We will keep standy in managed recovery mode. So, to make it primary we have to use
>ALTER DATABASE ACTIVATE STANDBY DATABASE

Is there any way, I can ACTIVATE standby DB so that it is consistent image of Original primary as of 11:15 AM(Point In Time recovery).

TIA..
np70