Once set up for automated deliveries, you will have full control over when your release will appear on SoundCloud.
You do this in the "Schedule" tool when creating a release. You will see that SoundCloud will appear as a DSP within the list. SoundCloud will be listed as a streaming store, so if you use the "Quick Set Options" it will simply fall in line with all other streaming stores.
You can set a custom date if you so wish or can opt-out of deliveries to SoundCloud altogether if you had a release with particular versions (streaming/download, for example)