Contact your school's financial aid office and ask for its records of when each loan was disbursed. The loan money is sent to the financial aid office, so the office will know when it arrived. This method has the advantage of providing federal student loan and private student loan information in one place.
Check your personal credit report for free through the Annual Credit Report website. The credit report will list each federal and private student loan separately, along with when the account was opened. This is the disbursement date. However, it might include only the month and year, rather than the full date.
Navigate to the National Student Loan Data System website and enter your personal information to locate all of your student loans issued through the federal government. After the website has listed all of your loans, click on each one to find its disbursement date. This method will not find private student loans.
Review your online account or paper statement from your lender to look up your loan's disbursement date. It should be clearly included in the loan information section.