Stephen Cheney wrote:
Minutes, maybe even only seconds, not days.
For undead, it's likely to just be the time it takes to summon the undead (maybe plus a little bit if the summoning time is really quick). By the time you can be like, "What? THESE undead, Mr. Paladin? I got these as a bequest from my grandfather. A terrible act, of course, but it seems like wasting them would be an even greater crime!" then the opponent is on shakier moral ground.
It'd probably vary for other stuff, and it's up for debate regardless. Guiding rule would probably be if you're clearly in the process of doing something awful and any LG court in the world would consider it open and shut, then you'd get it, but if you've put any reasonable doubt in between you and the act, you only have to worry about it if you did it somewhere where it also got you the Criminal flag.
The problem here that I still don't see addressed:
Undead-using necromancers are going to be flagged heinous 100% of the time that they're actually using the abilities they acquired in accordance with game mechanics. At least according to the blog, which says that you will retain the flag for as long as the evil act lasts (using raising undead specifically as an example) + the normal duration of the flag. Which means that anyone who chooses that particular character path will be a free kill with no rep loss.
As I see it, this is a problem from two positions.
First, it really sounds like it is going to be literally impossible to be a necromancer with a high reputation, which seems thematically absurd to me as many of the most notorious villains tend to be undead/associate with necromancy--Sauron and Count Strahd von Zarovich come to mind.
Second, the mechanical effect is going to treat an entire class (I know the game isn't class-based, but you know what I mean) as second-class players, giving them ALWAYS-ACTIVE (as long as they're actually using their abilities) punishments equivalent to a PKer or griefer. This is effectively conflating ROLEPLAYING an evil bastard (ripping imaginary souls from their rest) to BEING an a+#$!+! (griefing lower-power players, making the game unenjoyable for others).
I don't have a problem with (in-character) plumbing the depths of evil. Thematically, I recognize that all of the gods and most of the (unenlightened! ;) ) people will loathe me for it. But being a wicked necromancer should not make me an automatic kill-on-sight for everybody ever. If I am reading the blog correctly, this is an instance where the consequences for how you BEHAVE and how you ROLE-PLAY appear to be getting muddled.
Again, this all assumes that necromancers aren't ridiculously overpowered to make up for the fact that they're going to have to fight off every Tom, Dick, and Harry that they come across.