Likewise, we use a sample of upholstery, one half protected, the other plain. I always use a solvent protector as opposed to water based.
As for getting to it in 30 - 60 seconds, I am generally more optimistic and reckon within 5-10 minutes. If the protection is correctly applied then it should block any penetration for this period of time, especially on suites.
So far we have never had to go back to treat a stain that has penetrated the fabric or carpet.
AS an aside we have now also started promoting "Stain protection to new leather upholstery" as well as fabric.