Yeah, if you really want to bee like 100% sure you have the psu's ready before the miners arrive, then you can buy them from a different source.

These HP server power supplies are great, for example.
https://www.parallelminer.com/product/gold-rated-hp-1200w-power-supply-psu-9-pci-e-16awg-kit-for-antminer-l3-plus/

Use code slush for 5% discount.