Finishing sides a day apart

I'm building an L shaped desk out of butcher blocks, one 8 foot and one 4 foot.

I applied stain to both, doing both sides, one side a day.

I'm now at the point of applying poly, but I am worried about cupping. Before applying the stain, I tried using painters pyramids. Big mistake. They left deep indents, which I filled before the stain.

My main question is -

Now that I am going to be applying poly, I am worried that if I do one side, and then the other the next day, I run the risk of warping/cupping. But I don't want to set the wet poly bottom on pyramids and do the top, as I feel this will pull/chip the poly and leave indents.

Am I too worried? Will waiting a day in between sides be fine?

Two more questions - it's a chevron pattern, so going with the grain is not much of an option. Will it make a difference going lengthwise across the boards with the poly?

I also noticed orbital sander marks after the stain. Will these be amplified by the poly? I'm not really keen on sanding it all back down.