diff --git a/src/__tests__/LDClient-events-test.js b/src/__tests__/LDClient-events-test.js
index 8ed5e28..b345127 100644
--- a/src/__tests__/LDClient-events-test.js
+++ b/src/__tests__/LDClient-events-test.js
@@ -1,6 +1,6 @@
 import * as messages from '../messages';
 
-import { withCloseable } from 'launchdarkly-js-test-helpers';
+import { withCloseable, sleepAsync } from 'launchdarkly-js-test-helpers';
 
 import { respond, respondJson } from './mockHttp';
 import * as stubPlatform from './stubPlatform';
@@ -426,6 +426,28 @@ describe('LDClient events', () => {
     });
   });
 
+  async function expectDiagnosticEventAndDiscardRegularEvent(server) {
+    const req0 = await server.nextRequest();
+    const req1 = await server.nextRequest();
+    const expectedPath = '/events/diagnostic/' + envName;
+    const otherPath = '/events/bulk/' + envName;
+    let initEventReq;
+    if (req0.path === expectedPath) {
+      expect(req1.path).toEqual(otherPath);
+      initEventReq = req0;
+    } else {
+      expect(req0.path).toEqual(otherPath);
+      expect(req1.path).toEqual(expectedPath);
+      initEventReq = req1;
+    }
+    return JSON.parse(initEventReq.body);
+  }
+
+  async function expectNoMoreRequests(server, timeout) {
+    await sleepAsync(timeout);
+    expect(server.requests.length()).toEqual(0);
+  }
+
   it('sends diagnostic init event on startup', async () => {
     const server = platform.testing.http.newServer();
     server.byDefault(respond(202));
@@ -439,15 +461,11 @@ describe('LDClient events', () => {
       await withCloseable(client, async () => {
         await client.waitForInitialization();
         await client.flush();
-        const req0 = await server.nextRequest();
-        const req1 = await server.nextRequest();
-        const expectedPath = '/events/diagnostic/' + envName;
-        expect([req0.path, req1.path]).toContain(expectedPath);
-        const req = req0.path === expectedPath ? req0 : req1;
-        const data = JSON.parse(req.body);
+        const data = await expectDiagnosticEventAndDiscardRegularEvent(server);
         expect(data.kind).toEqual('diagnostic-init');
         expect(data.platform).toEqual(platform.diagnosticPlatformData);
         expect(data.sdk).toEqual(platform.diagnosticSdkData);
+        await expectNoMoreRequests(server, 50);
       });
     });
   });
@@ -467,15 +485,11 @@ describe('LDClient events', () => {
       await withCloseable(client, async () => {
         await client.waitForInitialization();
         await client.flush();
-        const req0 = await server.nextRequest();
-        const req1 = await server.nextRequest();
-        const expectedPath = '/events/diagnostic/' + envName;
-        expect([req0.path, req1.path]).toContain(expectedPath);
-        const req = req0.path === expectedPath ? req0 : req1;
-        const data = JSON.parse(req.body);
+        const data = await expectDiagnosticEventAndDiscardRegularEvent(server);
         expect(data.kind).toEqual('diagnostic-combined');
         expect(data.platform).toEqual(platform1.diagnosticPlatformData);
         expect(data.sdk).toEqual(platform1.diagnosticSdkData);
+        await expectNoMoreRequests(server, 50);
       });
     });
   });
@@ -497,6 +511,7 @@ describe('LDClient events', () => {
         expect(server.requests.length()).toEqual(1);
         const req = await server.nextRequest();
         expect(req.path).toEqual('/events/bulk/' + envName);
+        await expectNoMoreRequests(server, 50);
       });
     });
   });
diff --git a/src/__tests__/stubPlatform.js b/src/__tests__/stubPlatform.js
index 8a5dcac..18ff9a9 100644
--- a/src/__tests__/stubPlatform.js
+++ b/src/__tests__/stubPlatform.js
@@ -83,7 +83,14 @@ export function defaults() {
 
       makeClient: (env, user, options = {}) => {
         const config = { logger: p.testing.logger, ...options };
-        return LDClient.initialize(env, user, config, p).client;
+        // We want to simulate what the platform-specific SDKs will do in their own initialization functions.
+        // They will call the common package's LDClient.initialize() and receive the clientVars object which
+        // contains both the underlying client (in its "client" property) and some internal methods that the
+        // platform-specific SDKs can use to do internal stuff. One of those is start(), which they will
+        // call after doing any other initialization things they may need to do.
+        const clientVars = LDClient.initialize(env, user, config, p);
+        clientVars.start();
+        return clientVars.client;
       },
 
       setCurrentUrl: url => {
diff --git a/src/index.js b/src/index.js
index 8d07fe9..7fb8beb 100644
--- a/src/index.js
+++ b/src/index.js
@@ -43,9 +43,6 @@ export function initialize(env, user, specifiedOptions, platform, extraOptionDef
   const diagnosticsManager = diagnosticsEnabled
     ? diagnostics.DiagnosticsManager(platform, diagnosticsAccumulator, eventSender, environment, options, diagnosticId)
     : null;
-  if (diagnosticsManager) {
-    diagnosticsManager.start();
-  }
 
   const stream = Stream(platform, options, environment, diagnosticsAccumulator);