Well if you have already filed the 2018 return you must now WAIT and file the 3115 on the 2019 return per the instructions :
Form 3115
To make a change under Rev. Proc. 2011-14, the taxpayer must attach Form 3115 to a timely
filed (including extensions) original return for the year of the change. In addition, the taxpayer
must file a copy of Form 3115 with the IRS National Office no earlier than the first day of the
year of change and no later than when Form 3115 is filed with the federal income tax return for
the year of change.
