Hi Krothu, I'm user dd93 on the Virgin Media forum, I have commented on the same post as you. I was in the same position as you (until I got my new Lumia 735 less than 12 hours ago via Carphone Warehouse, [sim free, meaning no waiting for Virgin anymore, thank the lord!,]).
The VM team have always been annoyingly poor at giving out updates on this type of thing (unlike O2, who usually give out more detailed information when asked, unlike the standard "we have no information at the moment, we'll let you know when it is released" like Virgin do). The best response was the following:
"I can confirm that the Denim update is a software update but we've no further news on this currently". Yeah, no sh*t Sherlock, we knew that, we were asking about a release date, not what Denim was, we are not that stupid!
Hopefully, this supposed announcement on the 28th that another user claims will happen will be them releasing Denim, but I wouldn't hold your breath.