I will know it is time to short with impunity when the 21dma turns down.
If spx closes below 1550 next week, it turns down. Then, if spx closes below 1560 the next week, the 21dma turns down.
bottom line: new highs, even 1600 possible into early next week, but more likely we drop to 1540 and then rally back to 1565 followed by a drop back to 1490.
Just a hypotheses, nothing more, but is my trading plan.