It can take up to 21 days for the IRS to approve a tax return.
While you are waiting, you can create or log in to your account to check for any IRS messages: IRS View Your Tax Account.
Otherwise, if the timeframe goes beyond 21 days, see: IRS Let Us Help You for other ways to contact them.
For more information, see: My return is accepted but still not approved. Is there a problem? Should I be worried?