Installation on Raspberry Pi: add wait time (#29994)

- give an indication on how long it takes until the onboarding page becomes visible
- implements feedback from #29989

source/installation/raspberrypi.markdown

@@ -67,11 +67,17 @@ If Raspberry Pi Imager is not supported by your platform, you can use [Balena Et
 Within a few minutes after connecting the Raspberry Pi, you will be able to reach your new Home Assistant.
 
 - In the browser of your desktop system, enter <a href="http://homeassistant.local:8123" target="_blank">homeassistant.local:8123</a>.
-
+ 
     <div class="note">
     If you are running an older Windows version or have a stricter network configuration, you might need to access Home Assistant at <a href="http://homeassistant:8123" target="_blank">homeassistant:8123</a> or `http://X.X.X.X:8123` (replace X.X.X.X with your Raspberry Pi’s IP address).
     </div>
 
+- The time it takes for this page to become available depends on your hardware. On a Raspberry Pi 4, this page should be available within a minute.
+  - If it does not show up after 5 minutes on a Pi 4, maybe the image was not written properly.
+    - Try to flash the SD card again, possibly even try a different SD card.
+  - If this did not help, view the console output on the Raspberry Pi.
+    - To do this, connect a monitor via HDMI.
+
 Congratulations! You finished the Raspberry Pi setup!
 
 {% include installation_survey.html %}