Node Red- Google Calendar- Days remaining

Hello Guys,
I am trying to create a flow which picks up my Garbage Collection ( Bio, waste, Recycling) from my City agenda linked in google. The issue I am having is counting the number of days left before the pick up.

I have created a function in node red which looks like this :
var date1 = msg.time_now;
var date2 = msg.time_collection;
var Difference_In_Time = (date2) - (date1);
msg.days_remaining = Difference_In_Time;
return msg;

When I inject with the inject node I see the dates correctly but days_remaining stays at NaN

topic: “calendar.city”

payload: “off”

data: object

time_collection: “April 3, 2020 12:00 AM”

days_remaining: NaN

Can someone help me with how to calculate the number of days left before collection.

Thanks in advance Guys