You do not need to wait for a 1099-R next year that will probably require you to amend your 2016 tax return to report the excess on line 7 of your tax return - it can be entered this way and then ignore the 1099-R when it comes.
Excess 401(k) deferrals should be reported in:
Miscellionious Income ->
Other Income not reported on a W-2 ->
Other wages (yes) ->
House Hold employee (Continue) ->
Sick Pay (Continue) ->
Other earned income (yes) ->
Source of income (other) ->
Any other income - enter the amount and an explanation.
For information see IRS Pub 525 page 10
Quote from pub 525
"Excess deferrals. If your deferrals exceed the limit, you must notify your plan by the date required by the plan. If the plan permits, the excess amount will be distributed to you. If you participate in more than one plan, you can have the excess paid out of any of the plans that permit these distributions. You must notify each plan by the date required by that plan of the amount to be paid from that particular plan. The plan then must pay you the amount of the excess, along with any income earned on that amount, by April 15 of the following year.
You must include the excess deferral in your income for the year of the deferral unless you have an excess deferral of a designated Roth contribution. File Form 1040 to add the excess deferral amount to your wages on line 7. Do not use Form 1040A or Form 1040EZ to report excess deferral amounts.
Excess not distributed. If you don't take out the excess amount, you can't include it in the cost of the contract even though you included it in your income. Therefore, you are taxed twice on the excess deferral left in the plan—once when you contribute it, and again when you receive it as a distribution.
Excess distributed to you. If you take out the excess after the year of the deferral and you receive the corrective distribution by April 15 of the following year, don't include it in income again in the year you receive it. If you receive it later, you must include it in income in both the year of the deferral and the year you receive it. Any income on the excess deferral taken out is taxable in the tax year in which you take it out. If you take out part of the excess deferral and the income on it, allocate the distribution proportionately between the excess deferral and the income.
You should receive a Form 1099-R for the year in which the excess deferral is distributed to you. Use the following rules to report a corrective distribution shown on Form 1099-R for 2016.
If the distribution was for a 2016 excess deferral, your Form 1099-R should have the code 8 in box 7. Add the excess deferral amount to your wages on your 2016 tax return.
If the distribution was for a 2016 excess deferral to a designated Roth account, your Form 1099-R should have code B in box 7. Do not add this amount to your wages on your 2016 return.
If the distribution was for a 2015 excess deferral, your Form 1099-R should have the code P in box 7. If you didn't add the excess deferral amount to your wages on your 2015 tax return, you must file an amended return on Form 1040X. If you didn't receive the distribution by April 15, 2016, you also must add it to your wages on your 2016 tax return.
If the distribution was for the income earned on an excess deferral, your Form 1099-R should have the code 8 in box 7. Add the income amount to your wages on your 2016 income tax return, regardless of when the excess deferral was made.
Report a loss on a corrective distribution of an excess deferral in the year the excess amount (reduced by the loss) is distributed to you. Include the loss as a negative amount on Form 1040, line 21 and identify it as “Loss on Excess Deferral Distribution.”