It says on the site, after adding your card, you may begin to use it immediately. To me immediate means right away, not 24 hours later, or a week. In my case, it is not immediate.
In another case, my referral tried funding with her card, but when she clicks on submit, it doesn't go through, there is no confirmation. And when she asked for support, she waited a few days to get a copy paste answer with instructions on how to add a card and then fund with it.
Also don't you think waiting 4 or 5 days for support reply is very long?