Visiting Beijing for 4 days without China VISA.

If we arrive in Beijing early morning say around 6 AM on Day 1, then visit some of the sites in Beijing the next couple days, and leave on Day 4, we should be okay without a China VISA until 23:59 of Day 4, correct?
(Since the 72 hours starts from 00:00 the day following the entry date.)
The above is a worse case scenario since we cannot control the flight schedule in our vacation package deal.