BTC Spot ETF - After the approval

So we all know the market is pumping in anticipation of Bitcoin Spot ETF approvals, and many speculators expect approval in or before January. A lot of times in crypto (and the stock market in general), the event passes and the relevant asset crashes (because 'sell the news').

With the ETF it SHOULD be different, at least in my mind. However, I expect that the approvals will come, and many people will expect custodial purchasing to begin immediately.

So my topic for discussion - what will happen following the Spot ETF approval? Are we going to witness institutional players immediately purchasing in anticipation of future demand? Will these vehicles take a significant period of time to set up within brokerages, leading to a lull that causes the 'sell the news' crash to occur? Or will they have everything ready to go in the back end and immediately start offering their products?

Curious what everyone is anticipating