Why is my iCloud+ renewal date a day before the availed date?

Is “Renew: [Date]” and the payment date are the same for iCloud+ subscription? If yes, why is my renew date is the day before the date I avail it? For example, I avail it on March 5th, in my email invoice, the renew date is April 4th. So to make my payment date to the 5th, should I avail the iCloud on the 6th of the month?

[Re-Titled by Moderator]