Yes, we can setup schedule to turn on the Yeelight but it is not flexible.
For instance, my alarm might change from time to time.
Sleep as Android/ Alarmpad as my main alarm,they have integration with Tasker and will turn on the light when my alarm is triggered.
Yeelight is not going to be turned on based on my alarm, it will only be turned on based on the schedule in Yeelight app.
Moreover, Sleep as Android has it advantages.
When I start to track my sleep using phone/smart watch, I can schedule my sleep light to off 20 min after I fall asleep.
As for Xiaomi and Yeelight ecosystem, only Xiaomi Miband and Yeelight bedside lamp have this function.
When I wake up at night, to go to toilet, sleep tracking will be paused, thus it will automatically turn on the lights and off later when i fall asleep. With this app, all Yeelight product can have this function as it has tasker integration.
Currently, Sleep as Android only support Hue light but it seems that the developer has just started to work on it for Yeelight.
To me, it is a good news.