Our cycle runs from the 8th to the 7th of every month.
Interest is charged in advance for the upcoming cycle and is based on the number of days in that period. That means the interest you'll be accruing in the next period will be charged on the 8th (the start of your next cycle).
Interest is calculated off of your outstanding balance. If you pay in the middle of the cycle, it won't affect the interest charged for that cycle. It will, however, impact the outstanding balance for your following cycle.