Nobody was harmed by hearing about it on Tuesday rather than on Monday
Isn't that assumption where the whole argument for notifying selected parties in advance breaks down?
If you notify OpenSSL, and they push a patch out in the normal way, then anyone on the appropriate security mailing list has the chance to apply that patch immediately. Realistically, particularly for smaller organisations, it will often be applied when their distro's mirrors pick it up, but that was typically within a couple of hours for Heartbleed, as the security and backporting guys did a great job at basically all of the main distros on this one.
As soon as you start picking and choosing who else to tell first, yes, maybe you protect some large sites, but those large sites are run by large groups of people. For one thing, they probably have full time security staff who will get the notification as soon as it's published, understand its significance, and act on it immediately. For another thing, they probably have good automated deployment systems that will systematically patch all their affected servers reliably and quickly.
(I accept that this doesn't apply to those who have products with embedded networking software, like the Cisco and Juniper cases. But they can still issue patches to close the vulnerability quickly, and the kinds of people running high-end networking hardware that is accessible from outside a firewall are also probably going to apply their patches reasonably quickly.)
On the flip side, as long as you're giving advance warning to those high profile organisations, you're leaving everyone else unprotected. In this case, it appears that at least two different parties identified the vulnerability within a few days of each other, but the vulnerability had been present for much longer. There is no guarantee that others didn't already know about it and weren't already exploiting it. In general, though it may not apply in this specific case, if some common factor prompted the two contemporaneous discoveries, it might well be the case that additional, hostile parties have found it around the same time too.
In other words, you can't possibly know that nobody was harmed by hearing about it a day later. If a hostile party got hold of the vulnerability on the first day, maybe prompted by whatever also caused the benevolent parties to discover it or by some insider information, then they had a whole day to attack everyone who wasn't blessed with the early knowledge, instead of a couple of hours. This is not a good thing.