diff --git a/dev-packages/e2e-tests/test-applications/nestjs-basic/tests/schedule-instrumentation.test.ts b/dev-packages/e2e-tests/test-applications/nestjs-basic/tests/schedule-instrumentation.test.ts
index aa8a90c66cd5..0717b5074b59 100644
--- a/dev-packages/e2e-tests/test-applications/nestjs-basic/tests/schedule-instrumentation.test.ts
+++ b/dev-packages/e2e-tests/test-applications/nestjs-basic/tests/schedule-instrumentation.test.ts
@@ -2,13 +2,19 @@ import { expect, test } from '@playwright/test';
 import { waitForError, waitForStreamedSpan } from '@sentry-internal/test-utils';
 
 test('Sends exceptions to Sentry on error in @Cron decorated method', async ({ baseURL }) => {
-  const errorEventPromise = waitForError('nestjs-basic', event => {
-    return (
-      !event.type &&
-      event.exception?.values?.[0]?.value === 'Test error from schedule cron' &&
-      event.exception?.values?.[0]?.mechanism?.type === 'auto.function.nestjs.cron'
-    );
-  });
+  // The job throws the same error on every tick, so the Dedupe integration drops all but the first
+  // one unless another error is sent in between. That first error may predate this test.
+  const errorEventPromise = waitForError(
+    'nestjs-basic',
+    event => {
+      return (
+        !event.type &&
+        event.exception?.values?.[0]?.value === 'Test error from schedule cron' &&
+        event.exception?.values?.[0]?.mechanism?.type === 'auto.function.nestjs.cron'
+      );
+    },
+    0,
+  );
 
   const errorEvent = await errorEventPromise;
 
@@ -23,13 +29,18 @@ test('Sends exceptions to Sentry on error in @Cron decorated method', async ({ b
 });
 
 test('Sends exceptions to Sentry on error in @Interval decorated method', async ({ baseURL }) => {
-  const errorEventPromise = waitForError('nestjs-basic', event => {
-    return (
-      !event.type &&
-      event.exception?.values?.[0]?.value === 'Test error from schedule interval' &&
-      event.exception?.values?.[0]?.mechanism?.type === 'auto.function.nestjs.interval'
-    );
-  });
+  // See the @Cron test above for why this looks back to app startup.
+  const errorEventPromise = waitForError(
+    'nestjs-basic',
+    event => {
+      return (
+        !event.type &&
+        event.exception?.values?.[0]?.value === 'Test error from schedule interval' &&
+        event.exception?.values?.[0]?.mechanism?.type === 'auto.function.nestjs.interval'
+      );
+    },
+    0,
+  );
 
   const errorEvent = await errorEventPromise;
 
diff --git a/dev-packages/test-utils/src/event-proxy-server.ts b/dev-packages/test-utils/src/event-proxy-server.ts
index 627b3995ba05..d5130dc2fe53 100644
--- a/dev-packages/test-utils/src/event-proxy-server.ts
+++ b/dev-packages/test-utils/src/event-proxy-server.ts
@@ -334,12 +334,17 @@ export function waitForEnvelopeItem(
   });
 }
 
-/** Wait for an error to be sent. */
+/**
+ * Wait for an error to be sent.
+ *
+ * Pass `timestamp` to look further back than the moment of the call, e.g. `0` for an error the app
+ * emits on its own, before any test can start listening.
+ */
 export function waitForError(
   proxyServerName: string,
   callback: (errorEvent: Event) => Promise<boolean> | boolean,
+  timestamp: number = getNanosecondTimestamp(),
 ): Promise<Event> {
-  const timestamp = getNanosecondTimestamp();
   return new Promise((resolve, reject) => {
     waitForEnvelopeItem(
       proxyServerName,