Didn't Darla's take less than a day? When Dru turned her, I mean. I thought it was early in the morning when Dru bit her, and then she rose that evening. Could have conceivably been close to 24 hours, but then again....it could have been 10. Maybe it has something to do with what time the vampire bites the victim, if it's 3 am, then there wouldn't be time before the sun comes up. If it's 10 pm, it could happen before the sun comes up the next morning? In Lawson's case, they were in a sub, no worries about the sun at all!we've seen a wide range of vamp rise times.