Obsibrain isn't a direct replacement of a typical calendar with time of events. Since Obsibrain does not come (at least for now) with notifications, I decided to not go further with events and time of day. Right now your only possibility is actually to add a task named "my appointment at 8-9am" and add it to your day like "today" and see it in your daily planning.

→ https://github.com/uphy/obsidian-reminder

Fair enough, though I don't think the lack of notifications would be a deal breaker for a calendar like system. Sure some people may want notifications but others might not want notifications at all haha. Might be worth implementing it without notifications and then down the line if notification support is added in then add the ability to have notifications