It would be nice if you could set the time you want to practice, so you stay consistent.

You could set a time for 7:00 A.M. and then set it to 7:00 P.M. or whenever, that way, you get twice as much practice in one day.

Also, maybe allow the time of the lessons to be flexible whenever is convenient for us.

For example: lessons are 30 mins, but maybe you don't have that much time that day, so you could change it to 5 min, 15, etc.