How long does it take for Xanax to set in and calm you down?

I may take 2 or even 3 0.5mg over a few hours but I don’t get helped, instead it kicks in the following day making me sleepy, groggy and heavy-headed. When I need it during an “attack” it doesn’t help. What do you do? How do you take such medication? What is your approach? Do you take anything more effective? Seems I am drugging myself up for no reason.