The only thing you are doing that will temporarily hurt your score is that you opened so many accounts at one time. The average age of you credit accounts is a factor in your credit score so when you open several accounts all at once it pulls down that average. Also opening several accounts at once makes you look like you are desperate for credit which will also temporarily hurt your score, although the negative impact from this is likely to be offset by the fact that your ratio of total balances to total available credit will have improved.