Hi Erica,
I introduced another language lessons to my son when I noticed that he was comfortable with LR and wanted to see more lessons.
I then added another language lessons after he was done watching the daily English sessions.
I started with showing new contents to him once a day, then gradually add more lessons according to his cues and attention span.
In a good day, he can watch LM/LR-English/LR – Thai/ LR – French /Reading Bear/ and EK in one sitting...and still want more! In a not so good day, we just watch EK, and then I let him choose whatever he wants to see and that makes him happy.

Hope this help.
Elle