diff --git a/ui/app/models/config-ui/message.js b/ui/app/models/config-ui/message.js
index fdab790b54b5..4dccd5dfbf69 100644
--- a/ui/app/models/config-ui/message.js
+++ b/ui/app/models/config-ui/message.js
@@ -3,6 +3,7 @@
  * SPDX-License-Identifier: BUSL-1.1
  */
 import Model, { attr } from '@ember-data/model';
+import timestamp from 'core/utils/timestamp';
 import lazyCapabilities, { apiPath } from 'vault/macros/lazy-capabilities';
 import { isAfter, addDays, startOfDay, parseISO, isBefore } from 'date-fns';
 import { withModelValidations } from 'vault/decorators/model-validations';
@@ -109,7 +110,9 @@ export default class MessageModel extends Model {
     editType: 'dateTimeLocal',
     label: 'Message starts',
     subText: 'Defaults to 12:00 a.m. the following day (local timezone).',
-    defaultValue: addDays(startOfDay(new Date()), 1).toISOString(),
+    defaultValue() {
+      return addDays(startOfDay(timestamp.now()), 1).toISOString();
+    },
   })
   startTime;
   @attr('dateTimeLocal', { editType: 'yield', label: 'Message expires' }) endTime;
@@ -126,7 +129,7 @@ export default class MessageModel extends Model {
 
   // date helpers
   get isStartTimeAfterToday() {
-    return isAfter(parseISO(this.startTime), new Date());
+    return isAfter(parseISO(this.startTime), timestamp.now());
   }
 
   // capabilities
diff --git a/ui/lib/config-ui/addon/components/messages/page/create-and-edit.js b/ui/lib/config-ui/addon/components/messages/page/create-and-edit.js
index 8ba4c827a75e..d0116a58e942 100644
--- a/ui/lib/config-ui/addon/components/messages/page/create-and-edit.js
+++ b/ui/lib/config-ui/addon/components/messages/page/create-and-edit.js
@@ -11,6 +11,7 @@ import { service } from '@ember/service';
 import { action } from '@ember/object';
 import Ember from 'ember';
 import { isAfter } from 'date-fns';
+import timestamp from 'core/utils/timestamp';
 
 /**
  * @module Page::CreateAndEditMessageForm
@@ -63,7 +64,7 @@ export default class MessagesList extends Component {
       const modalMessages = this.args.messages?.filter((message) => message.type === 'modal') || [];
       const hasExpiredModalMessages = modalMessages.every((message) => {
         if (!message.endTime) return false;
-        return isAfter(new Date(), new Date(message.endTime));
+        return isAfter(timestamp.now(), new Date(message.endTime));
       });
 
       if (!hasExpiredModalMessages && this.args.hasSomeActiveModals && this.args.message.type === 'modal') {
diff --git a/ui/tests/integration/components/config-ui/messages/page/create-and-edit-test.js b/ui/tests/integration/components/config-ui/messages/page/create-and-edit-test.js
index e08430ed6285..254f3b1ed08f 100644
--- a/ui/tests/integration/components/config-ui/messages/page/create-and-edit-test.js
+++ b/ui/tests/integration/components/config-ui/messages/page/create-and-edit-test.js
@@ -14,6 +14,7 @@ import { format, addDays, startOfDay } from 'date-fns';
 import { CUSTOM_MESSAGES } from 'vault/tests/helpers/config-ui/message-selectors';
 import timestamp from 'core/utils/timestamp';
 import { GENERAL } from 'vault/tests/helpers/general-selectors';
+import sinon from 'sinon';
 
 module('Integration | Component | messages/page/create-and-edit', function (hooks) {
   setupRenderingTest(hooks);
@@ -21,14 +22,14 @@ module('Integration | Component | messages/page/create-and-edit', function (hook
   setupMirage(hooks);
 
   hooks.beforeEach(function () {
+    const now = new Date('2023-07-02T00:00:00Z'); // stub "now" for testing
+    sinon.replace(timestamp, 'now', sinon.fake.returns(now));
     this.context = { owner: this.engine };
     this.store = this.owner.lookup('service:store');
     this.message = this.store.createRecord('config-ui/message');
   });
 
   test('it should display all the create form fields and default radio button values', async function (assert) {
-    assert.expect(17);
-
     await render(hbs`<Messages::Page::CreateAndEdit @message={{this.message}} />`, {
       owner: this.engine,
     });
@@ -46,11 +47,14 @@ module('Integration | Component | messages/page/create-and-edit', function (hook
     assert.dom(CUSTOM_MESSAGES.field('message')).exists();
     assert.dom('[data-test-kv-key="0"]').exists();
     assert.dom('[data-test-kv-value="0"]').exists();
-    assert.dom(CUSTOM_MESSAGES.input('startTime')).exists();
     assert
       .dom(CUSTOM_MESSAGES.input('startTime'))
-      .hasValue(format(addDays(startOfDay(timestamp.now()), 1), datetimeLocalStringFormat));
-    assert.dom(CUSTOM_MESSAGES.input('endTime')).exists();
+      .hasValue(
+        format(addDays(startOfDay(timestamp.now()), 1), datetimeLocalStringFormat),
+        `message startTime defaults to midnight of following day. test context startTime: ${
+          this.message.startTime
+        }, now: ${timestamp.now().toISOString()}`
+      );
     assert.dom(CUSTOM_MESSAGES.input('endTime')).hasValue('');
   });