gulp.task('Copy images to build', () => {
    return gulp.src('source/images/**/*', {since: gulp.lastRun('Copy images to build')})
            .pipe(gulp.dest('buld/images'))
});

gulp.watch('source/images/**/*', gulp.series('Copy images to build'));

npm install touch

'use strict';

var cp = require('child_process');
var gulp = require('gulp');

gulp.task('reset', function() {
  // In gulp 4, you can return a child process to signal task completion
  return cp.execFile('touch -d "2 hours ago" source/images/**/* ');
});

npm i gulp-exec

'use strict';

var gulp = require('gulp');
var exec = require('gulp-exec');

gulp.task('reset', function() {
  return gulp.src('./**/**')
    .pipe(exec('touch -d "2 hours ago" source/images/**/*'));
});