How to connect autoincrement with auto_date_stamp - google-apps-script

Question

I have autoincremment in my google scripts. I would like add script with fixed timestamp. And connect with auto_increment in one time.
I started auto_increment script and next I start insert_timestamp
function auto_increment() {
var AUTOINC_COLUMN = 0; //start column
var HEADER_ROW_COUNT = 340;// start row
var spreadsheet = SpreadsheetApp.getActiveSpreadsheet();
var worksheet = spreadsheet.getSheetByName("Sheet 1");
var rows = worksheet.getDataRange().getNumRows() - 1;
var vals = worksheet.getSheetValues(1, 1, rows+1, 2);
for (var row = HEADER_ROW_COUNT; row < vals.length; row++) {
try {
var id = vals[row][AUTOINC_COLUMN];
Logger.log(id);Logger.log((""+id).length ===0);
if ((""+id).length === 0) {
// Here the columns & rows are 1-indexed
worksheet.getRange(row+1, AUTOINC_COLUMN+1).setValue(row);
}
} catch(ex) {
// Keep calm and carry on
}
}
}
function insert_timestamp() { //function onEdit() I cannot because I need fixed date one day
var s = SpreadsheetApp.getActiveSheet();
var r = s.getActiveCell();
var tz = Session.getScriptTimeZone();
if( r.getColumn() != 0 ) {
var row = r.getRow();
var time = new Date();
time = Utilities.formatDate(time, tz, "dd.MM.yyyy");//"dd.MM.yyyy hh:mm:ss");
SpreadsheetApp.getActiveSheet().getRange('C' + row.toString()).setValue(time);
}
}
When I write on cell "E" scripts insert new ID and timestamp "dd.mm.yyyy" and fixed when I change text in cell "E" date fixed the last.
Thank you for your help