I usually give it 72 hours after the deployment to see somewhat final numbers from stats.

Well that was frustrating – I wrote a long reply yesterday, and see that it never appeared here!
Anyway … It's interesting that you both say 72 hours is the point that you go through your stats. I too have found in general it is the highest peak of activity in my own and customer mailings. But I still think it is important to assess your own list's activity to see if it's just identified opens after 72 hours or if there are more of the all-important clicks and conversions happening in that waning tail of activity from the send.
As to if there is a difference between b2c and b2b, I don't think there is a marked difference. I think 'differences' come down to a company's product and/or services – and their sales life cycle. Also, I think there is an element of the recipient's perception as to how quickly they need to interact with your email. For example, if there's a very time sensitive offer – the peak of activity will be very soon after the mailing. In emails that are viewed as providing information-rich front-of-mind content, there is less urgency to handle it right away. I suspect people are more inclined to get to it when they have time.