How to deal with end of year 529 distribution that didn't go thru until Jan 2, 2018?

Hello - We have a 529 plan for our child who just started attending college in the fall of 2017.  I tallied up his qualified expenses at the end of December 2017 and submitted a request for a distribution for that amount.  However, due to the fact that it was our first withdrawal from this account, it took a couple of extra days to process and the transaction ended up being executed on January 2 of 2018.  So, I did not receive a 2017 1099-Q for the amount withdrawn, even though the amount was attributable to 2017 expenses.

Should I just let this go and attribute the above expenses to 2018 when I do the 2018 taxes?  Or... something else?  Just in case this affects the answer, we cannot take advantage of any other educational tax credits.

Thanks!