I've always just had to wait. Some that I thought would be hypo ended up being super hypo and vice versa. Someone else may be able to give you some sort of sign, but I've never seen any definitive sign at birth
Some super hypos hatch out with slightly faded brownish stripes instead of black ones. I've had a number of pairs hatch out this year where one came out with dark velvety black stripes and the other with paler, brownish stripes (I may be able to get a picture when I come back from vacation). As they develop, the lighter one has consistently become superhypo and the other a hypo. They are the product of a SHTCT x PRS cross.