Immediately. Your download link is emailed the moment the payment clears, and the whole premium library is open from that first minute.
There is no waiting period and nothing for us to switch on at our end. People who subscribe at midnight are downloading at one minute past.
How long the link keeps working
For as long as the subscription runs. It renews once a year on its own, and the same link keeps opening the same page, which by then holds more titles than it did when you joined.
The link stops working if a payment fails or after you cancel. If a card expires and the charge bounces, update it and the access comes straight back.
What you keep afterwards
Everything you downloaded. Those MP3 files sit on your device like any other audio, and they keep playing long after the subscription ends.
What ends is access to the page, so anything you never got round to downloading is behind the door again. Worth remembering in the last month of a subscription you are not renewing.
A word on downloading everything at once
The temptation on day one is to take the whole library. You can, and the "Download All" button is right there.
Listening to it is the other question. Most people see the first changes after two to four weeks on one program, so a folder of forty titles is a way of finishing none of them. There is a short answer on how many to run at once.
Take the files, then pick one or two and stay with them. The rest of the library is not going anywhere while you are subscribed.