In Bitcoin land most of the gains are booked within a very small time frame. It wouldn't really surprise me that the actual pumping starts just a month before the halving, then sell off a day or two before the actual halving (sell the news event), then trend up from there and really explode later on.
Sellers are going to front run one another knowing the event is coming. In 2016, BTC crashed 30% 3-4 weeks before the halving. With Litecoin earlier this year, it crashed nearly 2 months before. This makes timing impossible.
I do not believe that the halving is priced in yet, but what does somewhat bother me is that so many more people are focusing on events nowadays. There is no shortage of youtubers and whatnot pointing out the block halving, certain pattern formations, etc.
People always focus on events, news, etc. It's just the easiest way for their brain to justify price movements. That'll never change. The prevailing sentiment I see is still "the halving is already priced in" which bodes well for Q1.
I don't think the halving is priced in, I just see it as a non-event for the market. The halving will show up in market over many months, not as an immediate event. I could see the price going either way or doing nothing, depending on how the various market forces that want to make a statement about the halving and push it up or down around that date end up balancing out.
I think the reason the halving is a long term delayed effect is because there is a lot more pre-existing Bitcoin being traded each day than any amount that is hitting the market from recent mining rewards. So in the short term, regular market forces, irrespective of halving, are much more influential to the price than the mining reward change. But over many months the smaller amount of new Bitcoin being added to the world, and therefore added to the markets, gains more and more pressure on the price.
Bitcoin's halvings are like a tidal wave. At the event it'll only cause a small ripple that won't even be noticed among the normal waves of the market (unless big whales really want to force the market to take notice of the event). As time progress the wave heads toward land and starts to slowly exert an upward force, once the wave is close enough for everyone to see a FOMO breaks out and the wave becomes huge and starts creating market forces itself. People don't freak out from the tiny change when the event happens (this year), they freak out when they realize that after many months of gradual upward pressure the price is above the old ATH and continuing to go up. Enter FOMO (probably next year).