Welcome to flyertalk! You were definitely not ready to apply if you didn't read even enough of the terms and conditions to know that the first year's annual fee was not waived on your SW (or whatever) card. Much like rent, gym membership and virtually everything else, the fee is charged at the beginning of the period, if it is not waived for the first year. But you got the card and it will likely give you at least $500 in value, so enjoy!

Get cards that work for you, keep them for 11 months, cancel them or take a retention bonus, and don't worry. No one will be clawing back your miles.