Here is information regarding your question from an IRS FAQ's:
Why does it take so long for the funds to show up in my account?It takes additional time for refunds to be processed after leaving the IRS, and for financial institutions to accept and deposit them to bank accounts and products like debit cards. Also many financial institutions do not process payments on weekends or holidays, which can affect when refunds reach taxpayers.
The IRS states it can take up to 5 days or more in some cases.