Wait until you complete your 2018 tax return to report the 529 Plan distribution received in 2018. Keep records of your expenses that align with each distribution from the plan.
From your last statement, it sounds like the 529 Plan covered all of your dependent's education expenses. As long as the earnings and basis of the amount withdrawn were used for qualified education expenses, the distribution is tax-free.
See this TurboTax article Information on 529 Plans for additional details.
Note: 529 Plans are very liberal in what qualifies as an education expense. Room and board qualify too.
