From the founders perspective, what goal or milestone can we make happen sooner? The standard accelerator model takes the onward funding round as that goal - bringing it to 3-months instead of 12+-months.

For your startups, the goal doesn't have to be a funding round, but it should be a founder goal that is clearly defined such as an early client, a loan, or a validated business model. It doesn't even need to be objective or measurable, as long as you can somehow evaluate it. A clear definition of this goal will help make other design decisions, and will be the bedrock for improvement with every cohort.