Hello! I am new here as this is just my second thread. My family and I are only Bronze so can only seat select (for free) from a week before the flight. I was wondering if the "7 days" was 168 hours before the flight time or 168 hours before midnight in the UK?

The reason I ask is that I noticed almost all of the seats together are taken on our IAH-LHR flight in business and I have concerns I will end up separated from my children. Yet, I don't want to pay $600+ to seat select for four of us just for one flight.