Thank you for sending that! You should definitely be able to store the data values as timestamps in Firebase by sending them as either Date() or Moment() objects.
There's a thread discussing this on our Community Forum as well that I believe you came from actually.
What you're doing looks correct and should work 
Out of curiosity, if you click anywhere in you Value box, what does the green preview show nextSchedules as? Is it an array of strings or date objects? I want to double check if the string to date conversion is successful at this step.
