I would always wait for a pull back. Bounces from the pullbacks have been very swift and fast.
That is the only way I would enter.
It is necessary whenever we see an all time high. A dip will come for sure and then a pull back will come. That's a good strategy of yours if you usually do that.
Determining if it's the peak and knowing when it's about to pull back lies on how you see and understand the market every all time high.