Today, I got the Sneak quest and it is a quest that I am still trying to figure out which cards to use after the change in the starter packs. Some of my favored cards aren't available anymore and the change in summoners have a big impact as well.
So, after a good start and it looked like i could promote to Silver III today, I then suffered a series of losses which put me back lower into Bronze I. So, it looks like a single credit reward for today.
If I could promote tomorrow that would be massive as well but anything before day 10 is pretty good in my opinion. Promoting early does mean you face tougher opponents although it has gotten better with the rule changes as more similar quality opponents promote as well so there's a bigger pool of same level opponents to match with.