Sometimes you may not find SOA option in gallery in Jdev.
After you've checked for proper installation, check extensions, if it still doesn't appear, remove the jdev working folder - you can see that in Jdev-->About-->Properties
Usually its under Users/<yourUser>/AppData/Roaming/Jdeveloper
Remove this folder and restart jdev, you should see the soa studio options now.
After you've checked for proper installation, check extensions, if it still doesn't appear, remove the jdev working folder - you can see that in Jdev-->About-->Properties
Usually its under Users/<yourUser>/AppData/Roaming/Jdeveloper
Remove this folder and restart jdev, you should see the soa studio options now.