It's much simpler, more straightforward, and more robust to pause as soon as possible than to 'agree to pause in the future, and then do it at just the right moment'. Several reasons:

• Pausing doesn't happen in an instant. It will, in practice, likely take at least weeks if not months for an enforceable pause to be implemented once everyone agrees it is time. In that period, capabilities development will continue until the absolute last moment.
• The shorter the runway from the present AI status quo to truly dangerous capabilities, the more fragile the pause will be. And the longer we wait, the more complex the necessary measures will be to enforce the pause and prevent rogue actors from covertly advancing the frontier, because we'll have less time to safely detect them and stop them.
• Fewer points of failure. To agree to pause at some point in the future, you both have to get people to agree to that future goal, then when the time comes you have to get them to agree again. Each distinct time that everyone has to agree on something, there's an opportunity for failure/deception/defection.
• Relatedly, if a bunch of bigwigs announce that we're agreeing to pause, but at some point in the future rather than right now, that gives lobbyists for the frontier AI companies, and for AI accelerationism in general, a useful signal to rev up efforts to lobby against a pause. It might prompt them to throw tens of millions, even hundreds of millions, into anti-pause lobbying and PR, whereas an immediate pause agreement may catch them off guard and deny them this opportunity.
• This might likewise be a signal to frontier AI companies that they should borrow hard against future earnings, scale up staffing and compute as fast as possible, and do everything in their power to advance capabilities as much as possible before the pause. It might also motivate them to advance internal deployments even further ahead of external deployments than is presently the case.
• Political capital is easier to build for the former than for the latter, especially beyond narrow technical circles, because it's a simpler, more intuitive, and more emotionally satisfying goal.
• It's inherently difficult to know just 'when the right moment' is. There are error bars to this determination, and the longer we wait, the narrower the acceptable error bars become.