As long as it's flagged in the system, you can redeem right away.

I think the birthday cake has no connection with the number of drinks you bought right? Correct me if I'm wrong.

It's tied to your birth date.

Have you registered your card? If yes, just login and check it.

Or ask the barista to check for you.

Fastest: 2-5 mins
Slowest: up to 48 hours

I used my relative's card last Friday. The birthday month is in Jan. Bought the drink, walked back to office and check the starbucks system. Bday cake was there. I think it took around 20 mins by that time. I guess I should have checked it immediately.

Will check again with my sis' card. Yes, both cards genuine bday month in jan.

Not quite true. There was once after I bought the drinks, then I checked the Reward page after 5 mins and saw the Free cake has been updated. Went back to redeem the cake but the barista say its not updated yet. Went back again after another 5 mins, the barista said the same thing, no rewards in the system yet. Gave up then.

mine was different with you,cuz i registered quite a number of cards under same email and still get free drink upon activation,until recently,no more free drink and went and register under diff email.