Gregory, this is from Eurobet's terms and conditions:
2a. The amount of 25 chips will be added to GBP, EUR and USD account holders’ Casino chip balances within 48 hours of wagering (staking) a total of 625 chips or more from their own funds on any play for real game within the Eurobet Casino, and having followed the procedure in point 1.
And point 1 is just that you need to transfer money to the casino and enter the bonus code. I see now that it's not a big bonus (I could have sworn it was 50 when I first signed up), but for a WR of just 625, it's not bad. And if I remember correctly, the minimum is 1 pound or dollar. As for the 48 hour thing, I think it was immediate both times I've done it so far. In other words, as soon as I had wagered 625, another 25 appeared.