You can apply for as many credit cards as you want in one day, but that doesn’t mean you should. Every time you apply for a credit card, you will get a hard report on your credit report. This can lower your credit score by a few points each time you apply for a credit card.
Waiting between credit card applications can ensure you don’t get see a drop in your credit report. It’s recommended you wait at least 90 days between credit card applications.