For a while now you have been able to schedule iOS updates on Supervised devices in the Intune portal. Recently a new option was introduced in the iOS Update policy to “Delay Visibility of Software Updates”.
Pay close attention to the difference between delaying Visibility and actually delaying the update. A lot of admins first thought (Including me) by setting up a policy like the one below which will install Updates on a Sunday between 9 and 5 and has a delay of 30 days would mean that AFTER 30 days on the next Sunday the update will install between 9 and 5. However this is incorrect, what actually happens is the update installs as soon as it gets to Sunday between 9 and 5 and ignores the 30 days “Delay”. All this setting is really doing is stopping the end user from seeing the update on say Friday and installing it manually.
In order to create an iOS update policy which actually delays the install for 30 days you would need to set it up again with a 30 day delay of visibility but on the Days, Start and End time make sure there is no window for the install to complete. Below is a working example of how to block an iOS device from updating for 30 days. On Day 31 the update will be visible to the end user for them to manually install.