If a lane is going to expand should the left lane be taken prior to the expansion?
Simply: no. Move over only once there is a left turn lane. My preference is to arrive there towards the start of the left turn lane because that’s what other road users are expecting.

There are two parts to the answer. First, the law allows you to use the left turn lane, and in most places requires you to do so if you make that turn. But it also requires that you keep to the right as far as practicable, which means not moving into the left lane in anticipation of the left turn lane.

Second, safety. Your idea of crossing as a pedestrian is the best way if you’re not confident. Better is to ride across the road you’re on, then stop and wait for the lights to change. When they do, start riding when it’s safe, even if you haven’t walked all the way across that road. 

When the road is that busy, I’d be looking for gaps in the traffic and trying to move when those occur. A lot depends on your speed relative to the motorists. (edit) So if you can, cross those lanes when the lights are red. Stationary cars rarely hit anyone :) 

When there’s a big difference, even experienced cyclists will often fake hook (see below) or pedestrian across. But if you can sprint up to a near-enough speed, or the motorists are kind to cyclists, it’s usually quite feasible to switch lanes over to the turn lane. I find signalling works a lot of the time, and it’s worth trying. Put your arm out, see if someone slows down.

There are a few useful guides on how to do this. The one from the Canadians seems reasonable, and this guidance seems sensible



Note that in some places hook turns are legal. They’re common in Melbourne, Australia and are used in a few cycle-friendly cities around the world. Some people like them as a cycle safety measure, but in my view they’re insanely dangerous unless motorists are expecting them. If someone “runs the orange” they will hit anyone making a hook turn. Motorists do that a lot in some places. 

Cars regularly get them wrong in Melbourne, but relatively rarely with fatal consequences, as you often get when a motorist hits a cyclist. You’re better to do a “fake hook” — ride most of the way across with the pedestrians, turn and stop in front of the cars that are about to get a green light. Technically, that’s illegal, but it’s safe and easy.