google apps script - Trigger every 14 days starting on a specific date -

i'm trying trigger spreadsheet in google sheets reset every 14 days need start doing on date (it's company time sheets not that's relevant). here's have works, triggering every 14 days...

function test() {  scriptapp.newtrigger("14day_trigger")    .timebased()    .everydays(14)  browser.msgbox('testing!'); 

i want start 14 day cycle 2015, 06, 12. tried .atdate ...

function test() {  scriptapp.newtrigger("14day_trigger")    .timebased()    .atdate(2015, 06, 12)     .everydays(14)  browser.msgbox('testing!'); 

but gives error -

already chosen specific date time at() or atdate().

can me?

create 3 functions:

function triggeratdate() {   scriptapp.newtrigger("atdatetrigger")     .timebased()     .atdate(2015, 06, 12)     .create(); };  function 14day_trigger() {   scriptapp.newtrigger('resetitself')     .timebased()     .everydays(14)     .create(); };  function resetitself() {   spreadsheetapp.getactivespreadsheet().getsheets()[0].clearcontents(); }; 

then run first function inside of script editor. once one time trigger has run, no longer needed, delete it.

you wait day want trigger run from, manually create 14 day trigger on day.