Zyrtec - How long after I take my first pill should I get some relief from allergies?

That is not true. I have been taking zyrtec-d for years and it takes effect within 10-15 minutes and that is with yogurt, toast, coffee, and supplements.
For instance, I started itching from head to toe today and no hives. Within 10 minutes, I began to obtain relief; not total but enough to take the edge off. Another time, while taking an antibiotic, broke out with hives everywhere and took the zyrtec-d and all disappeared within two doses of 12 hour strength.
Yes, while everyone is different, it does not generally take that long to begin working

I forgot to add that I have terrible allergies living in NC and the I note that zyrtec-d takes approx 20-30" to notice relief. Additionally, the 12 hour strength is better as the 24 strength wears off much to quickly, in my experience. Other brands are available and if one stops working aa well, trade around.