Apple TV+ Yearly Subscription

I have used my 1 year free trial of Apple TV+ several months ago, and now would like to pay for a yearly subscription. However, the app doesn't offer me the yearly subscription, only the monthly. I know that I'm supposed to activate the monthly subscription, and then change it to yearly in Subscriptions, but I was wondering if I do that, will it be changed to yearly immediately or at the end of the paid month? i.e. Will I be charged $4.99 + $49.99, or it will change to yearly at once and deduce the $4.99 from the $49.99 for the whole year?

Thanks!