best time to port out number

That is correct. The amount will be prorated based on the cancellation date.

The best time to port out is on your last day of your billing cycle, so you will not lose the auto-pay discount.

So it can't be April 11 to May 12.

If the billing period starts April 11 then it ends May 10.

If the billing period ends May 12, then the billing period starts April 13.

So you need to make sure you have your billing period correct. 

Now to avoid any unexpected charges, it may be unavoidable with how koodo sets things. 

-If you cancel 12:01am on start of the new billing day you will be charged for prorated 1 day (no auto pay discount applies, but if it is given it will be reversed on the next bill) 

-if you cancel 11:59pm on the last day of your billing period, koodo may (and this is a big maybe) reverse the auto pay discount as it technically applies to a full billing cycle and I'm sure if koodo will consider this not a full Billing cycle 

Good catch Dennis. I got it backward. The bill was from April 12 to May 11.
If it is true that a $10 fee is charged at the time of closing a postpaid account just because the Auto-pay is part of that process, the it deserves some push back. The Community says a monthly account is automatically closed when its number is ported out. It might be understandable if the final bill had to be collected by other means than Auto-pay. But all of my bills were paid in full by Auto-pay justifying the discount every time. If Koodo sees a need to send another bill after my account is closed then feel free to withhold the discount, but sending an additional bill just because I erase my banking information when I don’t owe for any services rendered. Well, we will see how that goes. 

I am referring to credits only applying to full billing cycles. 

Reports on this community is that if you cancel before a full Billing cycle, the account is charged back the credit. 

https://www.koodomobile.com/en/terms/service-terms

Thanks Dennis. I’m aware and understand Koodo policy. I chose to port the postpaid number to the prepaid account today (5 days early). It required callback assists from both prepaid and postpaid assists. Ivania of prepaid assist assured me that my postpaid had been cancelled and there would be no clawback of the Auto-pay discount. I was surprised to find that my access to postpaid self serve would remain active for the same 3 months as the non payment grace period provides. It now describes my postpaid account as cancelled with a remaining balance of (credit) -$7.02 that stems from 5 days of unused service. My apprehension because of Community threads appears on to be unfounded.  

I would hold off on any declarations until your next detailed pdf invoice or 2 arrives

awe Dennis…  I really wanted to believe the call back reps. For me to receive another postpaid bill would mean the reps are ill informed or deliberately misleading… and they were so helpful and friendly. Either way, this was only an exercise to provide first hand information clarification to the Community. After all it’s only a few dollars. I yield to your expertise since I’m new here. Will this thread still be open in a couple of months for me to supply a final update?

If the thread gets archived, you can create a new thread.  If you mentioned you said all this in an old thread, we can look it up