What is the relevant time to assess whether a vehicle is an immediate hazard?

The relevant time to assess whether a [sic] approaching vehicle is an immediate hazard was considered at 413 of Raie v. Thorpe: It is my respectful opinion that the evidence I have related fully supports the finding of the learned trial judge that, when the male appellant made his left turn, the respondent's car was so close to the intersection as to constitute an immediate hazard, and so the male appellant ought to have yielded the right of way. With deference, it appears to me that the punctum temporis at which the question of immediate hazard and right of way arises is the moment before the driver who proposes to make a left turn actually commences to make it and not some earlier time. In my view the punctum temporis in this case was not when the male appellant was stopped at the traffic light and made a left-turn signal, but the moment before he started up from his second stop. I consider that up to that moment the actions of such appellant were merely preparatory to the making of a left turn. In this regard he was following common practice on the part of motorists.