Good, can be better I experiment with Arduino Pro Mini with BT module HC-05. App and Arduino code works well. I would suggest free time interval input for timers, and auto reconect to remembered BT device when app starts. Also great would be clock times set for device(s) turning On, then Off, at specific times.
Save bluetooth device Please make this device remember the bluetooth device
Set of tutorials for developers who want to use Arduino to create cool projects.