If the task must start in the future, then you are correct.
If the task is already active, then just set a reminder. If the reminder time is greater then the current time, then it will trigger a notification today, otherwise it will be tomorrow.
At this iteration only the mobile apps will have the UI and OS integration to create notifications. But adding the desktop app support is relatively easy in the future.
Reminder times are synced between all devices, including the desktop app. In fact, a desktop app upgrade to
1.4.3 will be required for correct operation of the feature.
So if you set a reminder on an item, the reminder gets synced to ESS (as part of the item’s changes). Then when you open another mobile device, it will receive the reminder and schedule a notification locally.